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AIR   SERVICE 
MEDICAL 


WAR  DEPARTMENT    :     :    AIR  SERVICE 

DIVISION  OF  MILITARY  AERONAUTICS 

WASHINGTON,  D.  C. 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

1919 


(V/ 


J> 


'        c    «    e    ,«  c 


GIFT 


PREFACE. 


In  each  of  the  countries  at  war  there  is  a  fully  established  Air 
Medical  Service.  Early  in  the  development  of  the  Aviation  Service 
of  our  Allies,  and  even  earlier  in^jthe  German  Air  Service,  it  was 
found  essential  to  create  a  medical  Tlepartment  as  an  integral  part  of 
the  Air  Force.  The  French  and  the  Italians  for  the  past  year  have 
had  well-organized  Air  Medical  Services,  which  include  in  their 
personnel  many  of  the  foremost  specialists  of  these  respective  coun- 
tries. The  British,  whose  Royal  Air  Force  exists  as  a  separate  arm 
of  the  service,  have  a  separate  Air  Medical  Service  with  a  Surgeon 
General  of  Aeronautics.  In  our  own  Service,  this  work  has  been 
effectively  handled  by  a  division  of  the  Surgeon  (leneraTs  Office, 
assigned  as  a  part  of  the  Division  of  Military  Aeronautics. 

Aviation  is  new,  and  the  Air  Medical  Service  even  newer;  so  that 
for  educational  purposers  the  director  of  Military  Aeronautics  deemed 
it  advisable  to  issue  this  book.  Its  object  is  to  set  forth  Aviation's 
debt  to  Medicine  and  to  make  clear  the  part  played  by  the  Air 
Medical  Service  in  the  "winning  of  the  war  in  the  air." 

The  book  is  presented  in  two  parts.  Part  I  is  a  shorter  statement 
of  the  essential  facts  which  are  of  immediate  general  interest.  Part 
II  goes  into  greater  detail  and  is  for  the  information  of  those  who 
belong  to  the  Air  Medical  Service  or  of  those  who  desire  to  make  a 
more  thorough  study  of  this  new  work. 

3 


457928 


CONTENTS 


PART  I. 

Page. 

Chapter  I.  Aviation  and  its  medical  problems 7 

II.  The  selection  of  the  flier 17 

III.  The  classification  of  the  flier 23 

IV,  Maintenance  of  the  efficiency  of  the  flier 29 

PART  II. 

I.  The  organization  for  the  examination  of  applicants 37 

II.  The  establishing  of  67  physical  examining  units 41 

III.  Working  methods  of  the  physical  examining  units 55 

IV.  Significance  of  the  tests  composing  the  physical  examinations 65 

V.  Statistical  report  of  the  results  of  the  examinations  made  by  the  67 

physical  examining  units 83 

VI .  Report  of  officers  returned  from  overseas 95 

VII.  Manual  of  Medical  Research  Laboratory 137 

VIII.  The  work  of  the  Flight  Surgeon 377 

IX.  The  Physical  Director 391 

X.  The  food  problem  of  the  flier 411 

XI.  A  message  to  the  flier 423 

5 


3      >    >  »     *      J 


PART  I. 

CHAPTER  I. 
AVIATION  AND  ITS  MEDICAL  PROBLEMS. 


Wonderful  has  been  the  development  of  the  airplane — inconceiv- 
able has  been  the  neglect  of  the  MAN  in  the  airplane. 

Aviation  began  in  the  United  States  of  America.  The  genius  of 
Langley,  Chanute,  and  the  Wright  brothers  made  it  possible  to  main- 
tain in  the  air  a  machine  heavier  than  air.  Starting  as  a  scientific 
experiment,  aviation  has  developed  with  such  gigantic  strides  that 
to-day,  in  the  defense  of  our  Nation,  the  Air  Force  has  a  place  com- 
parable in  fighting  importance  with  the  land  and  sea  forces. 

Ever  since  the  time  that  man  lived  in  a  cave  and  was  obliged  to 
chase  his  food  or  be  chased  by  it.  he  has  dreamed  of  flying,  fie  has 
racked  his  brain  and  bruised  his  bod}'  in  futile  attempts  to  emulate 
the  bird.  At  various  stages  in  his  histoi*y  we  see  him  climbing  to  the 
top  of  precipices,  trees,  bridges  and  houses,  and  from  these  heights 
projecting  himself  into  space,  with  nothing  to  break  his  fall  except  a 
modified  kite,  parachute,  or  some  similar  contrivance,  and  landing 
below  with  many  regrets  and  broken  bones.  Gravitation  was  not  to 
be  defied  by  such  rudimentary  methods. 

Through  all  time  man  has  been  speeding  up.  The  savage,  finding 
himself  upon  a  snow-capped  height  and  desiring  to  go  to  the  valley 
below,  was  wont  to  set  himself  upon  a  piece  of  bark  and  slide  down 
to  his  destination ;  or,  desiring  to  go  down  the  valley,  he  stepped  into 
a  hollow  log  and  shot  the  rapids  of  some  swiftly  flowing  stream. 
Desiring  to  cross  the  plain,  he  subjugated  the  horse  and  used  him  as 
a  more  rapid  means  of  transportation.  Later  on  civilized  man, 
astride  a  pair  of  wheels,  propelled  himself  along  the  highway  by 
means  of  a  mechanical  device.  Then  the  steam  engine  was  invented, 
and  with  it  the  steamboat  and  locomotive,  which  enabled  man  to 
travel  with  increased  speed.  The  electric  trolley  car  appeared  soon 
after  the  perfection  of  the  electric  motor.  Eventually  came  the  gas 
engine,  and  with  that  the  automobile,  capable  of  even  greater  velocity. 
It  is  not  surprising  that  in  the  United  States,  the  least  mature  of  the 
progressive  nations  of  the  world,  this  speed  mania  broke  all  bounds 

7 


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AIR  SERVICE   MEDICAL. 


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and  man  flew  off  at  a  tangent  into  space.    The  Wright  airplane  had 
set  a  new  pace. 

Each  new  mode  of  travel  has  evolved  its  own  new  and  peculiar 
human  ills  and  medical  problems.  Reverting  to  the  savage,  we  can 
picture  a  new  variety  of  accidents  coincident  with  rudimentary 
tobogganing.  With  water  transportation  came  seasickness  and 
drowning,  with  the  various  methods  of  resuscitation.  Railroading 
developed  a  new  category  of  ills,  from  caisson  disease  to  "  railroad 
spine;"  railroad  signaling  emphasized  the  importance  of  normal 
color  perception.  With  the  development  of  the  electric  railway 
there  opened  up  a  new  chapter  of  ills  in  the  form  of  electric  shocks 
and  burns.  With  the  gas  engine  came  Colle's  fractures  from  crank- 
ing and  an  increasing  number  of  collision  accidents  with  the  ever- 
increasing  speed.  Now  with  the  airplane  come  the  new  problems  of 
air-sickness,  oxygen-vs'ant,  and  the  unprecedented  demands  on  the 
special  senses,  the  nervous  system,  and  the  heart. 

While  American  genius  made  possible  the  birth  of  the  airplane. 
its  extraordinaiy  development  in  such  a  short  space  of  time  is  di- 
rectly due  to  the  drive  of  necessity  arising  from  actual  warfare  in 
Europe.  Prof.  Langley's  theories  of  heavier-than-air  machines  were 
correct:  the  producers  of  airplanes  have  converted  them  into  realities. 
After  tlie  appearance  of  tlie  Wright  biplane,  however,  flying  in  this 
country  made  little  progress;  we  Americans  were  slow  to  appreciate 
the  possibilitie.s  of  this  new  invention.  The  Wright  brothers  took 
their  machine  to  P^urope.  whei'e  an  immediate  keen  interest  developed 
in  its  sporting  possibilities.  Avhich  appealed  particularly  to  the 
French,  Italians  and  English.  The  Cierman,  ever  watchful  of  any- 
thing calculated  to  enhance  the  value  of  his  war  equipment,  immedi- 
ately took  notice  and  began  airplane  experiments.  Thus  the  French. 
Italian  and  English  interest  had  its  root  in  the  appeal  of  the  plane 
to  sporting  instinct;  the  German  interest,  on  the  other  hand,  sprang 
from  "  Kultur,"  in  recognition  of  its  possibilities  as  an  additional 
weapon  of  war.  The  development  of  the  airplane  among  the  Allies 
is  a  story  of  sportsmanship;  among  the  Germans  it  is  part  of  the 
secret  annals  of  war  preparation.  During  the  early  stages  of  the  war 
air  superiority  lay  with  the  Germans  and  was  represented  mainly 
by  their  development  of  the  Zeppelin.  During  this  period  the  Ger- 
mans placed  their  trust  in  the  lighter-than-air  type  of  machine;  at 
the  same  time  they  did  not  neglect  the  heavier-than-air  type.  It 
was  not  until  1916  that,  under  the  spur  of  war  conditions,  both  bel- 
ligerents came  to  a  full  realization  of  the  immense  possibilities  of  the 
airplane  as  a  fa(;tor  in  battle.  It  is,  therefore,  the  other  nations  who 
have  developed  the  airplane,  and  we  now  look  to  these  nations  for 
advice  and  instruction  in  aeronautics;  it  is  a  case  of  the  pioneer  t^ak- 
ing  the  position  of  a  novice  in  his  own  field  of  endeavor. 


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LANGLEY  STEAM-DRIVEN  AERODROME   IN  FLIGHT  OVER   POTOMAC   RIVER  NEAR    QUANTICO,  VA., 

MAY  6,  1896. 


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QUARTER-SIZE  GASOLINE  MODEL,  LANGLEY  AERODROME,  IN  ONE  OF  ITS  FLIGHTS  OF  AUGUST  8,  1903, 

ON  THE  POTOMAC  RIVER. 
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CADET  APPROACHING  PLANE  WITH  INSTRUCTOR  ON  HIS  FIRST  TRIP.    THE  CADET 

IS   MERELY   A    PASSENGER. 


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A  CADET  AND  HIS  INSTRUCTOR. 


■•"    •_• 


INSTRUCTOR  IMPRESSING  UPON  THE  CADET  THE  USE  OF  THE  RUDDER. 


CADET  AND  INSTRUCTOR  IN  THE   MACHINE. 
The  instructor  is  assisting  the  cadet  who  is  experiencing  an  air  trip  for  the  first  time. 


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CADET  RECEIVING  FINAL  INSTRUCTIONS  BEFORE  GOING  ON  A  FLIGHT  ALONE. 
This  cadet  has  completed  his  preliminary  course  and  is  about  to  start  on  a  solo  flight. 


STARTING   OFF   ON  A  FLIGHT. 


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PILOT  AND  CADET  SLOWLY  AND  CAREFULLY  DESCENDING  TO  A  LANDING  PLACE. 


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CADET  DESCENDING  FOR  HIS  FIRST  LANDING. 


CADET   EXPERIENCES   FIRST   HALF   HOUR   IN   AN  AIRPLANE. 
The  instructor  made  a  perfect  landing  without  bumping,  much  to  the  satisfaction  of  the  student. 

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A  CADET  READY  FOR  HIS   FIRST  SOLO   FLIGHT. 


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A  CADET  AFTER   HIS   FIRST   SOLO   FLIGHT. 
Having  had  his  first  ride  he  smiles  all  over  upon  landing. 


•  AIR  SERVICE   MEDICAL.  11 

It  is  easy  to  see  how  the  necessity  for  attention  to  the  physical 
efficiency  of  the  pilot  came  to  be  overlooked ;  the  world  over,  everyone 
has  been  so  absorbed  in  the  one  eft'ort — to  increase  the  mechanical 
efficienc}'  of  the  airplane.  Every  thought  has  been  directed  toward 
making  each  successive  model  safer  and  faster. 

During  this  period,  representing  the  firet  two  and  one-half  years 
of  the  war,  the  pilot  was  not  selected  because  of  any  peculiar  fitness 
for  flying;  it  was  simply  a  question  of  whether  he  "had  the  nerve." 
At  one  time  circumstances  made  it  necessary  to  place  men  in  the 
Aviation  Service  who  were  "'  all  worn  out  by  the  more  trying  work  " 
of  the  Infantry  or  Field  Artillery.  The  viewpoint  was:  "  This  man 
is  no  longer  fit  for  ground  fighting;  therefore  he  will  do  for  the  air 
service."  The  result  of  this  policy  was  that  the  average  aviator  had 
a  very  short  time  of  usefulness  and  there  was,  to  this  extent,  some 
truth  in  the  persistent  rumor  that  the  ''  active  life  of  the  aviator  at 
the  front  was  only  a  certain  number  of  hours."  There  w^as  enormous 
avoidable  wastage.  Little  by  little  the  Aviation  Services  of  our  Allies 
have  come  to  realize  that  the  advice  of  their  medical  officers  was 
sound;  the  mental  and  physical  requirements  for  entering  the  Air 
Service  were  raised,  with  an  inunediate  saving  of  an  unlimited 
amount  of  money  and  personnel.  This  is  the  great  lesson  we  have 
learned  from  the  bitter  experience  of  our  Allies. 

The  popular  idea  that  a  flier  nuist  be  a  "  superman  "  is  utterly 
absurd.  It  would  be  much  nearer  the  truth  to  say:  "Anyone  can 
fly."  Flying  itself  is  now  just  as  prosaic  and  commonplace  as  riding 
in  a  motor  car,  and  not  more  dangerous.  To  consider  that  the  aviator 
at  the  front  is  in  greater  danger  than  his  brother  in  the  trenches  is 
ridiculous;  actual  statistics  prove  that  it  is  far  safer  in  the  air.  Fur- 
ther than  this,  instead  of  living  in  the  filth  of  the  trenches,  the  fight- 
ing pilot  returns  to  a  comfortable  airdrome  well  behind  the  lines, 
where  he  sleeps  in  comfort  and  one  might  even  say  in  comparative 
luxury. 

Nevertheless,  aviation  is  not  jncrely  spectacular;  it  does  have  its 
unique  problems  and  makes  its  unique  demands  upon  those  in 
this  service.  Nature  never  intended  that  man  should  fly.  From  the 
time  that  he  leaves  the  ground  until  his  return,  he  is  living  under 
unnatural  conditions.  Although  it  should  be  emphasized  again  and 
again  that  the  flier  at  the  front  is  safer  than  the  infantryman  in  the 
trenches  this  does  not  mean  that  we  should  belittle  the  conditions 
which  the  aviator  faces.  He  flies  in  an  atmosphere  lacking  in  that 
oxygen  which  is  the  " breath  of  life";  subjected  to  the  shells  of  anti- 
aircraft guns,  or  encountering  enemy  aircraft  at  any  moment;  with 
his  body  at  a  dizzy  height  and  hurtling  through  space  at  the  rate 
of  125  miles  an  hour — this  represents  the  daily  life  of  the  fighting 


12  AIE  SEEVIOE  MEDICAL. 

pilot.  The  aviator  himself  is  serenely  unconscious  of  the  effect  of 
these  conditions  upon  his  nervous  system;  he  naturally  regards  it 
as  "  all  in  a  day's  work."  Yet  in  attaining  altitudes  and  spending 
much  of  his  time  in  rarefied  air,  the  flier  is  defying  nature. 

The  conquest  of  the  air  represents  man's  maximum  achievement. 
There  is  no  combination  of  wood  and  wire  which  is  subjected  to 
such  a  variety  and  intensity  of  strain  and  stress  as  the  airplane; 
there  is  no  living  combination  of  muscle  and  nerve  which,  consciously 
or  unconsciously,  may  be  subjected  to  such  a  variety  and  intensity  of 
strain  and  stress  as  the  aviator. 

To-day  thousands  of  trained  mechanics  are  working  day  and  night 
upon  the  engines  of  our  airplanes;  thousands  of  expensively  trained 
riggers  and  saihnakers  are  tuning  the  wires  and  mending  torn  fabric ; 
thousands  of  hangars  are  provided  to  house  the  planes  when  they 
are  not  flying.  A  striking  discrepancy  is  noted  when  we  look  about 
to  see  what  is  being  done  to  take  care  of  that  infinitely  more  delicate 
organism — the  man  who  flies  the  machine. 

The  pilot  of  the  airplane  is  the  heart  and  brain  of  the  whole  flying 
apparatus.  The  engine  may  fail  through  lack  of  care,  but  the  pilot 
brings  the  machine  safely  back  to  the  airdrome.  A  carelessly  inspected 
wire  may  snap  in  the  air,  but  nothing  serious  results.  When  the 
pilot  breaks,  even  momentarily,  nothing  is  left  to  direct  the  flight, 
and  the  plane  and  engine,  no  matter  how  well  they  have  been  cared 
for,  crash  and  are  lost. 

The  mechanic  who  looks  after  the  troubles  of  the  engine  must  be 
an  expert.  Work  like  this  is  not  for  the  mediocre.  No  less  an  expert 
must  be  that  man  who  supervises  the  condition  of  the  pilot.  Flying, 
especially  in  the  military  service,  coupled  with  the  temperament 
peculiar  to  the  man  choosing  this  kind  of  work,  develops  a  most  ex- 
traordinary series  of  problems  and  complications.  Many  an  aviator 
in  a  short  time  becomes  a  subject  over  which  a  genius  in  medicine 
might  easily  become  discouraged. 

The  establishment  by  our  forefathers  of  the  West  Point  Military 
Academy  was  a  wise  forethought.  In  this  institution  a  curriculum  of 
four  years'  intensive  study  prepares  our  young  men  for  the  profession 
of  the  soldier.  In  this  war,  however,  an  important  and  novel  military 
situation  has  arisen;  even  West  Point  does  not  offer  a  solution  of 
this  problem.  The  Air  Fighting  Force  is  without  military  precedent 
to  furnish  instruction  in  all  its  details.  The  problems  of  this  war 
on  the  ground,  while  new  in  many  aspects,  still  could  be  met  by  the 
skill  of  the  engineer  and  the  tactician  with  fundamentals  furnished 
by  years  of  military  experience  and  study.  The  problems  of  the  pres- 
ent war  in  the  air  lack  the  accumulated  experience  of  previous  wars 
to  indicate  their  solution;  those  difficulties,  which  early  made  it 
apparent  to  our  Allies  that  an  air-fighting  force  has  its  own  poten- 


AIB  SEEVICB  MEDICAL.  18 

tialities  of  disaster,  presented  the  immediate  problems  of  our  Air 
Service. 

To  the  Air  Medifcal  Service  the  problems  were  presented  of  over- 
coming all  those  conditions  affecting  the  physical  fitness  of  the  man 
who,  leaving  his  natural  environment,  the  ground,  straps  wings  to 
his  body  and  soars  to  heights  into  which  even  the  eagle  dare  not  go. 
For  work  in  this  unnatural  environment  only  the  man  who  is  in 
every  way  physically  fit  should  be  selected. 

When  our  Air  Medical  Service  was  established  it  was  fortimate 
to  have  at  hand  a  series  of  reports  of  the  Air  Medical  Services  of  our 
Allies  by  medical  officers  who  have  attained  distinction  in  the  field 
of  scientific  research.  Birley,  Dreyer,  Haldane,  Flack,  Douglas,  and 
Priestly  among  the  British ;  Nepper,  Josue,  Lombaert,  Guilbert,  Gar- 
saux  among  the  French;  Gradenigo  and  Herlitzka  among  the 
Italians,  had  been  studying  for  years  the  physical  deterioriations 
peculiar  to  flying  which,  even  early  in  the  war,  so  emphasized  the 
military  importance  of  this  particular  problem  of  the  Air  Service. 

The  keynote  of  the  American  Air  Medical  Service  is  the  handling 
of  the  flier  as  an  INDIVIDUAL. 

During  the  early  part  of  the  war  the  German  method  of  air  fight- 
ing was  patterned  after  that  of  their  infantry ;  the  pilot  of  the  ma- 
chine received  his  commands  and  carried  them  out  regardless  of 
changing  conditions.  The  observer  in  a  two-seater  machine  gave 
the  pilot  his  orders,  just  as  an  infantry  officer  gave  orders  to  his 
subordinate.  There  were  only  a  few  picked  flying  officers,  usually  of 
high  social  position,  who  were  what  might  be  called  "  sportsmen." 
The  efficiency  of  the  German  Air  Service  was  greatly  increased  in  the 
year  1917  by  their  allowing  a  certain  freedom  of  action  to  their  pilots 
in  order  to  cope  vvith  the  more  speedy  allied  air-men  who  had  proven 
individually  far  superior  in  action,  spirit  and  initiative.  Infantry 
and  cavalry  which  strike  in  large  numbers  must  be  handled  as  a  single 
force :  they  must  have  coordination  and  absolute  oneness  of  action  or 
half  their  effectiveness  is  lost.  The  efficiency  of  such  troops  is  meas- 
ured by  the  successful  handling  of  a  large  striking  force  as  a  single 
unit.  The  aviator  is  the  rank  and  file  and  commanding  officer,  all  in 
one.  The  outcome  of  a  reconnaissance  flight  may  determine  the  fate 
of  thousands  on  the  ground;  but  it  is  the  flier's  individual  decision, 
initiative  and  action,  that  spell  victory  or  defeat  for  him. 

The  Air  Medical  Service,  devoted  as  it  is  entirely  to  the  study  of 
the  flier  as  an  individual,  naturally  falls  into  three  main  lines  of 
activity — the  Selection  of  the  Flier,  the  Classification  of  the  Flier,  and 
the  Maintenance  of  the  physical  efficiency  of  the  Flier.  These  three 
branches  of  the  Air  Medical  Service  are  presented  in  concise  form  in 
Part  I  of  this  book.  In  Part  II  is  given  a  fuller  discussion  of  these 
same  subdivisions. 


14  AIE  SERVICE  MEDICAL. 

Underlying  "  Selection  "  is  a  full  realization  that  it  is  possible  for 
a  man  to  fly  in  spite  of  one  or  many  handicaps;  the  object  to  be  at- 
tained, however — the  defeat  of  the  enemy — demands  that  only  such 
fliers  be  sent  against  him  as  are  the  very  best  air-fighting  material — 
not  merely  men  who  are  able  to  fly. 

"  Classification "  is  the  second  step.  The  flying  service  is  now 
highly  specialized.  Men  are  called  upon  to  perform  widely  diversi- 
fied classes  of  work,  such  as  pursuit,  reconnaissance,  photography, 
bomb-dropping  and  night-flying.  Not  every  aviator,  regardless  of 
perfect  training  and  physical  fitness,  is  necessarily  fitted  for  all 
types  of  air  activities.  There  is  a  marked  difference  in  the  individual 
ability  to  withstand  a  diminished  oxygen  supply;  this  has  made  it 
necessary  to  classify  the  fliers  on  an  altitude  basis.  By  means  of 
tests  applied  at  the  Medical  Research  Laboratory  at  Mineola,  Long 
Island,  and  at  the  branch  laboratories  in  the  various  flying  schools 
throughout  this  country  and  overseas,  fliers  are  being  classified  as 
fitted  for  low,  moderate,  and  high  altitudes,  night-flying,  and  other 
special  types  of  work. 

The  "  Maintenance  "  of  physical  efficiency  of  the  fighting  force  is 
the  supreme  function  of  the  Air  Medical  Service.  There  is  a  sharp 
contrast  between  the  work  of  selection  and  the  work  of  maintenance. 
In  selection  the  sole  object  is  that  all  questionable  material  be  kept  out 
of  the  service.  In  maintenance  the  great  object  is  that  every  aviator 
be  kept  in  the  service. 

When  an  airplane  begins  to  show  signs  of  trouble,  it  is  taken  off 
the  field  and  put  in  condition.  This  is  the  only  way  to  keep  a  plane 
in  commission.  When  the  flier  shows  the  first  signs  of  staleness,  of  nerv- 
ous exhaustion,  or  of  digestive  disturbance  he  must  be  "  overhauled  " 
by  a  medical  expert.  That  distinctly  American  product — the  Flight 
Surgeon — bears  the  same  relation  to  the  flier  that  the  mechanical  ex- 
pert bears  to  the  airplane. 

The  airplane  is  in  need  of  frequent  overhauling ;  the  flier  even  more. 
The  secret  of  prolonged  usefulness  of  any  aviator  is  that  he  be  kept 
constantly  fit.  The  Flight  Surgeon,  by  both  old  and  new  diagnostic 
methods,  supplemented  by  his  laiowledge  of  the  peculiarities  of  the 
individual  flier,  is  able  to  detect  very  early,  the  signs  of  deterioration. 
The  corrective  measures  to  be  applied  will  belong  to  one  of  three 
classes.  They  are  medical,  physical,  and  what  we  may  term  nutri- 
tional. The  medical  needs  constitute  especially  the  problem  of  the 
Flight  Surgeon.  In  order  to  supplement  his  work  and  take  care  of  the 
physical  needs  of  the  flier,  there  have  been  secured  for  the  Aviation 
Service  the  services  of  experienced  college  trainers.  These  men  have 
been  given  a  course  of  instruction  covering  the  special  aspects  of 
physical  training  as  it  applies  to  the  care  of  tbe  flier,  and  have  then — 
as  Physical  Directors — been  sent  out  to  each  flying  field  to  assist  the 


AIB  SERVICE   MEDICAL.  15 

Flight  Surgeon.  These  Physical  Directors  fill  a  special  need  in  the 
work  of  "  maintenance  "  in  that  they  bring  to  this  service  the  practical 
experience  already  derived  from  the  handling  of  athletes  in  colleges 
or  athletic  clubs. 

In  order  to  handle  most  successfully  the  third  class,  namely,  nutri- 
tional problems,  the  services  of  the  Nutrition  Officer  are  required. 
The  Nutrition  Officer  must  be  a  man  well  trained  in  the  knowledge  of 
food  values  in  relation  to  the  body  and  he,  under  direction  of  the 
Flight  Surgeon,  is  charged  with  not  only  the  problem  of  the  proper 
feeding  of  the  normal  flier,  but  especially  of  the  flier  suffering  transi- 
tory digestive  disturbance — a  type  of  defect  that  affects  greatly  the 
efficiency  of  the  flier  when  in  the  air. 

The  work  of  the  Air  Medical  Service  reached  its  culmination 
with  the  placing  of  a  Flight  Surgeon  in  each  flying  school  in  the  United 
States  where  his  work  in  the  "  care  of  the  flier  "  has  been  but  a  prepa- 
ration for  the  larger  service  to  the  aviator  who  is  actually  on  the 
fighting  front  overseas.  It  is  only  through  the  complete  Flight 
Surgeon  Service,  including  those  features  supplied  by  the  Physical 
Director  and  the  Nutrition  Officer,  that  the  flier  may  be  maintained 
at  his  full  efficiency  in  active  service. 

89118—19 2. 


CHAPTEE  II. 
THE  SELECTION  OF  THE  FLIER. 


T^Tien  it  was  announced  that  a  state  of  war  existed  between  the 
United  States  and  Germany,  it  at  once  became  apparent  that  a  tre- 
mendous number  of  aviators  must  be  secured  for  the  military  service 
within  the  shortest  possible  space  of  time.  The  medical  problem 
consisted  of  selecting  thousands  of  physically  acceptable  men  for  avia- 
tion and  placing  them  in  training  for  war  service  immediately. 

It  was  found  necessary  to  decide  upon  new  methods  of  physical 
examination  and  to  adopt  new  standards  of  physical  qualifications 
for  this  branch  of  the  service.  Before  our  entrance  into  the  war  con- 
siderable thought  had  been  given  to  the  problem  of  what  should 
constitute  the  physical  requirements  for  admission  into  the  aviation 
service,  and  medical  officers  had  been  in  conference  with  other  mem- 
bers of  the  medical  profession  who  were  interested  in  this  question. 
Due  consideration  also  had  been  given  to  the  study  of  the  require- 
ments formulated  by  England,  France,  and  Italy,  and  also  Germany. 
The  examination  according  to  amended  blank  609,  A.  G.  O.,  was  put 
into  operation  in  May,  1917,  and  it  is  worthy  of  note  that  this  same 
series  of  tests  remains  unaltered,  even  to  the  minutest  detail,  up  to  the 
present  time. 

The  judgment  applied  to  the  original  selection  of  those  to  consti- 
tute the  Air  Fighting  Force  of  the  United  States  was  not  based  upon 
an  attempt  to  decide  whether  or  not  the  individual  selected  would  be 
able  to  fly.  It  was  known  that  men  had  been  able  to  fly  in  spite  of 
one  or  more  physical  handicaps,  such  as  having  only  one  leg,  having 
one  eye,  having  tuberculosis,  or  being  cross-eyed,  or  having  one  col- 
lapsed lung,  or  being  well  over  50  years  of  age.  Instances  were  at 
hand  of  those  so  handicapped  who  had  been  able  to  learn  to  fly  and 
to  fly  well.  Ultimate  economy  as  well  as  immediate  efficiency  indi- 
cated unquestionably  the  wisdom  of  admitting  to  training  only  the 
very  best  material.  The  enormous  number  of  applicants  at  hand 
made  it  possible  to  maintain  the  highest  standards  in  selecting  men 
for  this  service.  It  had  been  demonstrated  by  the  experience  of  our 
Allies  that  careful  selection  would  avoid  the  expense,  in  time  and 
money,  of  training  large  numbers  of  those  who  would  not  make  good 
in  the  service.  Furthermore,  our  measuring  stick  was  chosen  in 
anticipation  of  peak-load  requirements.  It  was  realized  that  each 
man  entering  the  flying  service  might  be  called  upon  to  negotiate 

17 


18 


AIR  SEBVICE  MEDICAL. 


LOOPING. 

Success  in  looping  Impossible  if  the  aviator  has  any  "  mental  t-wists." 


•      AIB  SERVICE   MEDICAL. 


19 


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a 


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M   si 


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S 


O 


20  AIR  SERVICE  MEmCAL.      • 

critical  emergencies  in  the  air;  that  insufficient  oxygenation  coupled 
with  prolonged  nervous  tension  under  high  altitude  combat  condi- 
tions, actual  injury,  sudden  changes  in  circumstances  demanding  in- 
stant decision  and  action,  would  require  of  him  the  utmost  mental 
and  physical  capabilities. 

It  is  only  right  that  we  should  supply  for  our  air  fighters  as  good 
if  not  better  planes  than  those  used  by  the  enemy.  In  the  same  spirit, 
it  is  our  duty  to  bear  in  mind  that  when  an  American  aviator  meets 
a  German  aviator  the  outcome  of  the  encounter  may  easily  depend 
upon  which  of  the  two  possesses  the  better  vision  and  other  special 
senses,  the  better  nervous  system,  and  the  better  mental  and  physical 
equipment  in  general.  The  flier  starting  for  the  enemy's  lines  car- 
ries with  him  a  certain  potential  disaster  for  the  Hun.  The  one-eyed 
man  may  succeed ;  the  possession  of  two  eyes,  however,  would  render 
success  more  certain.  The  responsibility  of  the  Air  Medical  Service 
in  the  selection  of  the  flier  is  that  no  aviator  shall  fail  in  his  mission 
against  the  Hun  because  of  discoverable  physical  defect. 

In  order  to  make  the  examination  of  standard  character,  it  was 
necessary  to  make  the  tests  practicable  of  application  in  all  parts  of 
the  United  States  without  at  the  same  time  in  any  way  lowering  the 
requisite  rigid  standards  or  lessening  the  completeness  of  the  exami- 
nation. This  could  be  attained  only  by  (1)  the  standardization  of 
the  tests  and  (2)  the  standardization  of  the  examiners.  To  accom- 
plish this,  a  medical  officer  was  sent  to  each  of  35  cities  throughout  the 
United  States,  with  the  result  that  in  each  one  of  these  cities  there 
was  established  a  medical  unit  for  the  examination  of  applicants  for 
the  Aviation  Service.  The  requirements  of  the  examination  were 
fully  explained  to  each  unit,  so  that  not  only  the  same  equipment  was 
used,  but  also  exactly  the  same  technique.  This  made  it  impossible 
for  any  applicant  to  say,  "  I  wish  I  had  been  examined  in  a  certain 
city  where  the  tests  are  easy,  rather  than  in  a  certain  other  city  where 
the  tests  are  exacting."  Those  specialists  were  selected  who  were 
most  expert  in  the  practice  of  their  chosen  work;  where  a  new  type 
of  examination  was  essential,  such  as  the  turning-chair  tests,  those 
otologists  were  selected  who  were  familiar  with  these  tests,  and,  in 
addition,  they  were  given  intensive  training  by  medical  officers  sent 
for  the  purpose  of  establishing  a  uniform  technique.  Thus  in  a  few 
months  the  examination  was  put  on  a  uniform  basis  in  all  Physical 
Examining  Units. 

In  order  to  save  time,  already  existing  institutions,  such  as  large 
hospitals  or  State  universities,  with  their  equipments,  were  utilized 
as  these  examining  centers.  Volunteer  staffs  of  civilian  consultants 
were  locally  organized  and  the  work  of  the  Physical  Training  Units 
systematized  to  a  point  of  highest  efficiency,  with  the  result  that 


JUST  MISSING  A  FLAGSTAFF. 

Prompt  action,  intelligently  executed,  saved  this  flyer  and  his  machine  from  a  crash.    Fighting  in  the  ait 

makes  continual  demands  on  such  ability. 


>'i^tffliai8esdfe«a»a»k.  :2»2«w 


MAKING  A   PERFECT  LANDING. 
This  requires  perfect  stereoscopic  vision. 


20a-l 


FKiHTING  IN  THE  AIR  MAKES  THE  MOST  SEVERE  DEMANDS  ON  PILOTS. 
Only  the  most  fit  are  chosen  for  this  work. 


CADET  AMONG  THE  CLOUDS. 

A  situation  in  which  vision  is  of  little  use.    The  "  motion-sensing  "  portion  of  the  interval  ear  must 
be  normal,  or  the  pilot  can  not  detect  mjvem  mt  nor  mally. 
20a-2 


AIE  SEEVICE  MEDICAL.  21 

within  a  few  days  after  the  arrival  of  the  medical  oflBcer  the  units 
were  ready  for  work.  By  this  method  of  decentralization  the  ex- 
amination of  thousands  of  applicants  in  a  minimum  time  was  made 
possible.  Once  it  was  assured  that  those  charged  with  the  responsi- 
bility of  conducting  the  examination  were  fully  equipped  and  capable 
of  making  the  tests,  full  authority  was  vested  in  the  medical  officer  in 
charge.  Thirty-two  military  units,  later  established  in  the  divisional 
camps  of  the  United  States,  attended  to  the  examinations  of  the  en- 
listed applicants  for  air  training.  By  far  the  majority  of  applicants 
were  civilians,  however,  and  the  35  original  units  in  the  cities,  each 
examining  from  10  to  60  applicants  a  day,  soon  provided  the  thou- 
sands of  men  required. 

Attention  should  be  drawn  to  the  contribution  to  the  Government 
war  work  represented  by  the  vast  amount  of  professional  service 
rendered  without  pay  by  the  civilian  members  of  these  units.  These 
civilian  consultants  included  many  of  the  foremost  specialists  of  the 
United  States ;  were  the  services  rendered  by  them  to  be  represented 
in  terms  of  Liberty  bonds,  the  sum  total  would  constitute  a  very 
respectable  loan  without  interest.  It  is  worthy  of  special  mention 
that  in  addition  to  the  routine  examining  work  of  the  units,  the 
members  performed  many  hundreds  of  surgical  operations  enabling 
the  applicants  to  qualify  physically  for  this  service,  without  cost 
either  to  the  applicant  or  to  the  Government. 

A  public  meeting  was  held  in  each  city  under  the  auspices  of  the 
medical  profession  of  that  city.  The  mere  establishment  of  the  units 
was  by  no  means  all  that  was  accomplished  by  the  work  of  the  Medi- 
cal Department.  Throughout  the  United  States  there  was  no  lack  of 
interest  on  the  part  of  the  young  men  of  the  country  to  enter  the 
flying  service.  There  was,  however,  a  striking  need  for  authoritative 
information  regarding  the  Aviation  Service  and  how  to  go  about 
getting  into  it.  A  by-product  of  the  establishment  of  the  units  was 
the  stimulation  in  each  city  of  large  public  interest  in  this  branch  of 
the  service.  In  one  city  after  the  meeting  95  men  expressed  their 
desire  to  enter  this  service. 

In  the  rush  of  events  after  our  entrance  into  the  war  not  only  was 
there  a  lack  of  information  regarding  Air  Service,  but  there  was  a 
considerable  amount  of  misinformation,  most  probabl}^  attribut- 
able to  German  propaganda.  Throughout  the  country  was  spread 
the  information  that  the  average  life  of  an  aviator  was  only  a  few 
hours  of  actual  service.  Parents  were  given  to  believe  that  their 
sons  were  being  taken  for  an  almost  immediate  and  inevitable  sacri- 
fice. Furthermore,  there  was  not  a  city  in  the  United  States  in  which 
it  was  not  firmly  believed  by  the  public  that  the  much-discussed 
medical  examination  of  an  aviator  was  a  form  of  refined  torture. 
One  story  was  that  of  the  "  needle  test."    This  mythical  examination 


22  AIE  SERVICE   MEDICAID 

was  supposed  to  consist  of  placing  a  needle  between  the  candidate's 
forefinger  and  thumb,  blindfolding  him,  then  shooting  off  a  pistol 
behind  his  ear.  The  examiner  would  then  note  whether,  due  to  his 
supposed  lack  of  nerve,  the  applicant  had  pushed  the  needle  through 
his  finger.  Another  much-rumored  test  was  described  as  follows: 
When  the  applicant  least  expected  it  he  would  be  hit  over  the  head 
with  a  mallet,  and  if  he  regained  consciousness  within  15  seconds  he 
was  qualified  as  being  of  the  stuff  of  which  aviators  are  made.  It 
was  the  medical  officer  who  could  supply  the  needed  information 
and  also  demonstrate  the  utter  nonsense  of  this  prevailing  misinfor- 
mation. In  this  way  parents  were  assured  by  the  Surgeon  General 
that  their  sons  were  put  through  only  an  ordinary  physical  exami- 
nation to  insure  their  fitness  for  the  service,  and  that  for  their  own 
protection  they  would  not  be  accepted  unless  physically  sound.  The 
mystery  of  the  examination  was  removed  by  actual  demonstration, 
aided  by  moving  pictures. 

At  these  public  meetings  were  gathered  those  of  the  medical  pro- 
fession and  general  public  who  were  interested  in  aviation.  The 
interest  aroused  within  the  medical  profession  by  the  work  of  the 
Physical  Examining  Units  also  resulted  in  bringing  into  the  Air 
Medical  Service  a  large  number  of  specialists  whose  training  in  the 
examination  of  aviators  fitted  them  later  for  a  larger  sphere  of  use- 
fulness in  the  care  of  the  flier. 


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23a-4 


CHAPTER  ni. 
CLASSIFICATION. 


The  flier,  who  through  good  training  has  become  perfect  in  his 
technique  and  who  through  proper  care  is  physically  fit,  is  not  neces- 
sarily fitted  for  all  types  of  air  activities.  When  the  present  war 
first  began,  there  were  but  few  airplanes  and  what  airplanes  existed 
were  used  for  all  kinds  of  work.  If  an  airplane  and  a  man  could 
stay  in  the  air,  they  were  used  for  any  service  which  an  emergency 
might  call  for.  On  one  day  the  pilot  might  be  asked  to  go  across 
the  lines  on  a  reconnaissance  mission  and  with  the  same  machine, 
which  was  very  limited  in  climbing  ability  and  speed,  he  would  be 
called  upon  the  following  day  to  go  into  the  air  to  fight 

With  the  coming  of  improved  designs  and  the  more  skillful  manag- 
ing of  airplanes  by  fliers,  different  types  of  machines  have  become 
classified  into  special  groups  for  special  work.  The  flying  service  is 
now  highly  specialized.  Men  are  called  upon  to  perform  widely 
diversified  classes  of  work,  such  as  pursuit  or  scout  work,  recon- 
naissance, photography,  day  or  night  bombing,  artillery  observation, 
and  for  each  of  these  special  missions  the  pilot  is  provided  with  a  cer- 
tain type  of  plane  adapted  to  the  work  in  hand. 

Both  the  enemy  and  ourselves  divide  the  machines  used  for  service 
into  two  distinct  classes;  we  have  both  the  fighting  machines  which 
are  a  fast,  quick-climbing  type,  easily  and  quickly  maneuvered,  and 
heavier  machines  which  are  slower  in  action  and  capable  of  carrying 
almost  any  weight. 

It  is  easy  to  see  that  a  fast-climbing  machine  is  bound  to  carry 
the  pilot  to  greater  heights  than  the  slow,  weight-carrying  machines. 
Whereas  in  1915,  flying  rarely  exceeded  8,000  or  10,000  feet,  through 
improved  designs  scouts  of  to-day  climb  to  altitudes  even  as  high  as 
25,000  feet,  and  this  height  is  attained  in  a  very  short  space  of  time. 
The  nature  of  the  work  of  a  scout,  which  is  simply  hunting  out  the 
enemy  and  attacking  him,  also  necessitates  descents  from  high  alti- 
tudes at  tremendous  speed. 

Night  bombing  has  been  carried  out  at  altitudes  as  low  as  300 
feet.  Day  bombing,  in  order  not  to  reveal  the  objective  of  the  flight 
and  to  guard  against  concentrated  anti-aircraft  fire,  may  call  for 
flights  at  very  high  altitudes.     The  possible  necessity  of  attaining 

23 


24  AIR  SEEVTCE  MEDICAL. 

siich  altitudes  presents  a  nice  problem  when  we  consider  the  weight 
of  bombs  which  must  be  carried,  together  with  the  protective  equip- 
ment with  which  the  plane  must  be  loaded.  Reconnaissance  ma- 
chines rarely  get  to  high  altitudes  owing  to  the  necessity  for  more  or 
less  close  observation  of  the  ground,  and  machines  doing  this  work 
must  accomplish  very  low  flying  even  in  the  face  of  highly  concen- 
trated anti-aircraft  fire  and  enemy  activity  in  order  to  fulfill  their 
mission.  Machines  cooperating  with  the  artillery  which  have  to 
make  range  corrections  for  batteries  do  not  often  work  above  6,000 
or  8,000  feet.  From  this  we  can  see  that  the  machines  doing  the  types 
of  work  just  mentioned,  except  day  bombing,  fly  very  much  lower 
than  the  pursuit  or  scout  planes.  With  their  capacity  for  carrying 
a  larger  amount  of  fuel,  they  can  remain  in  the  air  for  very  long 
periods.  When  a  long  trip  is  to  be  made,  such  as  a  bombing  raid  far 
into  the  enemy  country,  at  least  four  or  five  hours  must  elapse  and 
the  pilot  is  apt  to  be  fatigued  to  the  limit  of  his  endurance.  Espe- 
cially is  this  the  case  in  cold  weather  and  under  the  long  strain  of 
an  extended  flight  encountering  anti-aircraft  fire  and  enemy  planes. 

Pilots  of  scout  machines,  on  the  contrary,  owing  to  the  speed  and 
climbing  ability  possessed  by  planes  built  for  this  type  of  work,  never 
stay  in  the  air  much  over  two  and  one-half  or  three  hours  on  account 
of  being  unable  to  load  up  their  machines  with  more  than  a  moderate 
weight  of  fuel.  But  they  have  to  go  to  tremendous  heights,  they  have 
to  change  those  heights  very  quickly  and  very  often,  and  they  are 
subject  to  quick  changes  of  temperature  as  well  as  sudden  variations 
in  oxygen  content  of  the  air. 

In  view  of  these  facts  the  Air  Medical  Service  realized  the  im- 
portance from  a  purely  military  standpoint  of  careful  classification 
of  fliers.  The  work  of  the  Medical  Research  Laboratory  has  demon- 
strated that  of  each  100  carefully  selected  fliers  only  61  are  physically 
and  mentally  capable  of  attaining  an  altitude  of  over  20,000  feet 
with  safety;  25  out  of  each  100  are  physically  and  mentally  unsafe 
at  altitudes  above  15,000  feet;  and  14  out  of  each  100  are  physically 
and  mentally  unsafe  at  altitudes  above  8,000  feet.  Or  that  61  of 
the  100  are  fit  for  any  type  of  air  work;  that  25  may  do  bombing; 
that  14  should  be  limited  to  reconnaissance  or  night  bombing.  Such 
classification  of  pilots  for  specific  duties  constitutes  a  new  factor  of 
conservation  and  safety  to  our  forces. 

The  feature  of  knowing  the  limitations  of  a  valuable  man  spell 
increased  efficiency. 

Just  as  the  pilot  is  provided  with  a  certain  type  of  plane  adapted 
to  the  work  in  hand,  so  the  plane  must  be  provided  with  a  pilot 
adapted  to  the  work  in  hand. 

It  is  true  that  in  the  absence  of  a  pilot  physically  and  mentally 
adapted  for  high-altitude  work  it  is  possible  to  use  one  who  is 


ATK  SERVICE   MEDICAL.  25 

adapted  only  for  low-altitude  work  by  equipping  him  with  an 
apparatus  to  supply  oxygen  according  to  his  needs.  Supplying 
oxygen  to  fliers  has  been  a  subject  of  much  experiment  and  study 
during  the  past  two  years  both  by  the  enemy  and  by  the  allies. 
The  British  have  used  an  oxygen  apparatus  of  satisfactory  type  for 
two  years — the  Dreyer  apparatus;  this  type  of  apparatus  is  being 
produced  in  the  United  States  in  increasingly  large  numbers,  and  at 
the  same  time  modifications  and  improvements  are  being  constantly 
made.  In  the  very  nature  of  things,  however,  it  is  impossible  to  count 
upon  adequate  and  ready-to-serve  oxygen  supply  for  each  aviator  in 
each  machine  which  emergency  may  send  into  high  altitude.  Until 
the  final  absolute  perfection  of  oxygen  apparatus  for  the  flier  and  the 
equipping  of  each  high-altitude  plane  has  been  accomplished,  cogni- 
zance must  be  taken  of  altitude  rating  of  the  flier  in  "  selecting  the 
man  for  the  job." 

Physiologic  studies  on  men  undertaking  to  live  at  high  altitude, 
such  as  Pike's  Peak,  haA'e  proven  that  a  very  complex  series  of 
changes  occur  before  their  bodies  become  able  to  live  normally 
with  less  oxygen.  This  is  acclimatization,  and  this  occurs  in  the 
man  living  on  Pike's  Peak,  but  not  in  the  aviator  who  alternates 
constantly  between  high  and  low  altitudes. 

The  flier  must  undergo  abrupt  changes  in  atmospheric  pressure 
and  oxygen  supply.  Atmospheric  pressure  plays  a  very  unimpor- 
tant role;  the  whole  problem  resolves  itself  into  a  deprivation  of  the 
normal  oxygen  supply.  The  fact  that  there  is  "oxygen-want"  at 
high  altitudes  suggested  that  any  piece  of  apparatus  that  would 
permit  the  breathing  of  a  reduced  amount  of  oxygen  could  be  used 
to  test  the  ability  of  men  to  withstand  high  altitudes.  The  Flack 
liag  was  the  prototype  of  the  rebreathing  apparatus  which  has  been 
developed  in  the  Medical  Research  Laboratory  and  perfected  for  such 
tests.  By  means  of  this  apparatus  the  aviator  rebreathes  air  con- 
fined in  a  tank,  from  which  he  gradually  consumes  the  oxygen.  As 
the  percentage  of  oxygen  decreases  the  aviator,  in  effect,  is  slowly 
ascending  to  higher  altitudes.  In  the  course  of  25  to  30  minutes  he 
lowers  the  oxygen  content  of  the  air  in  this  tank  to  8  or  7  per  cent, 
which  is  equivalent  to  attaining  altitudes  of  25,000  to  28,000  feet. 

Another  method  of  attaining  the  same  result  is  by  means  of  the 
diluting  apparatus,  which  supplies  directly  to  a  mask  over  the  face 
whatever  proportions  are  desired  for  a  mixture  of  air  and  nitrogen. 
All  of  these  tests  have  been  standardized  and  confirmed  by  the  low- 
pressure  tank,  in  which  the  air  is  rarefied  to  correspond  to  any  given 
altitude. 

By  a  comparison  of  the  percentage  of  oxygen  to  which  the  aviator 
succumbs  when  on  the  low-oxygen  tests  it  is  possible  to  determine 
precisely  the  altitude  at  which  the  aviator  would  fail  were  he  in  the 


26  AIB  SERVICE  MEDICAL. 

air.  This  determination  is  made  on  the  ground,  without  danger 
either  to  the  aviator  or  to  his  machine,  and  has  been  taken  as  the 
basis  for  the  classification  of  aviators  now  in  use  by  the  Medical 
Research  Laboratories. 

It  may  be  noted  that  these  tests  of  the  ability  of  an  aviator  to 
withstand  oxygen  reduction  could  not  be  made  safely  in  the  air,  as 
the  effects  of  oxygen-want  are  insidious  and  often  the  aviator  suc- 
cumbs very  suddenly  and  completely  when  his  limit  is  reached. 

The  effect  of  low  oxygen  upon  the  mental  processes  of  the  aviator 
varies  greatly  in  the  individual.  The  aviator  usually  becomes  men- 
tally inefficient  at  an  altitude  at  which  there  is  as  yet  no  serious  fail- 
ure of  his  vital  bodily  functions.  If  he  were  sent  to  an  altitude 
which  his  heart  could  safely  stand,  his  efficiency  would  nevertheless 
suffer  because  his  brain  is  not  acting  properly.  By  simple  tests  of 
mental  alertness  during  rebreathing  it  is  easy  to  determine  that  one 
flier  becomes  mentally  inefficient  at  15,000  feet,  in  sharp  contrast  to 
another  aviator  who  has  his  full  mental  powers  up  to  and  beyond  an 
altitude  of  25,000  feet. 

Low  oxygen  has  a  marked  effect  upon  vision.  Oxygen-want  ex- 
aggerates to  a  marked  degree  any  existing  defect  of  the  eyes.  In 
many  young  healthy  men  the  rebreathing  tests  made  manifest  eye 
defects  which  may  have  eluded  detection  by  the  most  expert  exami- 
nation. Crash  reports  have  demonstrated  that  a  large  proportion 
is  due  to  such  eye  defects.  Again,  in  night  flying  it  is  most  impor- 
tant that  the  flier  shall  be  able  "to  see  well  in  the  dark."  Many 
aviators  are  able  to  fly  well  without  any  difficulty  in  the  daytime,  but 
not  at  night.  Laboratory  tests  determine  definitely  which  individ- 
uals possess  the  ability  to  see  well  at  night. 

"  Stunting "  is  essentially  an  internal-ear  problem.  During  and 
after  rapid  turnings  the  flier's  brain  is  receiving  impulses  from  his 
semicircular  canals.  Nothing  can  control  or  alter  the  sending  or 
receiving  of  these  impulses.  These  impulses  produce  sensations  of 
motion.  Fliers  vary  greatly  in  their  ability  to  interpret  correctly 
the  significance  of  these  impulses.  Experience  alone  enables  the 
aviator  to  familiarize  himself  with  the  meaning  of  these  impulses; 
those  who  develop  the  greatest  ability  in  this  respect  naturally  fall 
into  the  scout-pursuit  class.  Those  who,  in  spite  of  training,  are  still 
disturbed  or  bewildered  by  stunting  should  be  reserved  exclusively 
for  straight  flying,  such  as  bombing  and  photography.  Again,  the 
peculiar  demands  of  night  flying,  reducing,  as  it  does,  at  times  to 
the  vanishing  point,  information  coming  from  the  eyes,  require  a 
type  of  flier  who  possesses  the  keenest  ear  sense  for  the  detection  of 
movement. 

The  rebreathing  test  is  also  very  valuable  in  determining  staleness 
in  aviators.    As  staleness  is  caused  by  frequent  exposure  to  high 


2Sa-l 


RE-BREATHER. 


2Ca-2 


DREYER   DILUTING   APPARATUS. 


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VERTICAL  BANK.     SIDE   SLIPPING— 2,000  FEET  IN   THE   AIR. 
Poor  balancing  ability  can  thus  endanger  pilot  and  machine. 


AIR  SERVICE   MEDICAL. 


27 


THE  CHASE. 
A  critical  moment  when  tlie  nervous  system  should  be  in  good  order. 


28  AIE  SERVICE  MEDICAL. 

altitudes,  evidence  of  this  is  easily  obtained  by  means  of  the  rebreath- 
ing  machine.  Where  originally  a  flier  was  able  to  tolerate  an  alti- 
tude of  20,000  feet  or  more  before  showing  certain  symptoms  of  stale- 
ness,  after  flying  for  100  hours  or  more,  it  is  frequently  found  in  re- 
examination by  means  of  the  rebreather  that  he  is  stale  and  is  unable 
to  tolerate  the  oxygen  reduction  equivalent  to  10,000  feet.  Incipient 
cases  of  staleness  are  thus  easily  detected.  The  detection  of  the  early 
cases  of  staleness  is  of  greatest  importance  in  that  it  makes  it  possible 
to  ground  a  man  for  a  certain  period  and  thus  enable  him  to  recover 
entirely,  whereas  if  this  condition  is  not  diagnosed  early  it  will  pro- 
gress until  a  point  is  reached  where  it  is  impossible  for  the  aviator 
to  "  come  back  "  and  his  services  as  a  flier  are  thus  lost  to  the  country. 
When  the  staleness  becomes  marked  the  aviator  is  very  liable  to  faint 
in  the  air,  thus  losing  his  life  and  wrecking  his  machine.  By  periodi- 
cally examining  aviators  the  first  signs  of  staleness  will  be  detected 
early  and  measures  can  be  taken  to  conserve  the  efficiency  of  those 
who  would  otherwise  be  inevitably  lost  to  the  service. 


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CHAPTER  IV. 
THE  FLIGHT  SURGEON. 


The  Flight  Surgeon  constitutes  the  ultimate  "answer  "  to  the  main- 
tenance problem  of  the  Air  Medical  Service. 

In  the  foregoing  chapters  has  been  presented  the  work  of  the  selec- 
tion of  the  aviator  and  of  the  classification  of  the  aviator.  The  Air 
Medical  Service,  however,  does  not  end  here.  It  is  all  very  well  to 
have  chosen  with  great  care  those  hand-picked  men  who  constitute 
our  Air  Force  and,  thanks  to  the  enormous  number  of  applicants,  to 
have  adhered  to  the  highest  standards  in  their  selection.  It  is  all 
very  well  to  have  medical  specialists  classifying  fliers  and  deter- 
mining their  peculiar  fitness  for  special  branches  of  aerial  activity. 
This,  however,  by  no  means  marks  the  limit  of  usefulness  of  the 
Air  Medical  Service.  The  one  immediate  need  of  the  military  avi- 
ator in  all  the  services  of  the  world  is  an  organization  for  his  up- 
keep and  care  in  actual  service.  After  two  and  one-half  years  of 
bitter  experience  it  was  gradually  borne  in  upon  the  allies  that  at 
the  end  of  a  certain  amount  of  continuous  service  the  flier  begins  to 
show  unmistakable  signs  of  deterioration,  and  the  economical  thing 
to  do  is  to  relieve  him  temporarily  from  active  flying.  This  was  a 
new  thought  in  aviation.  Up  to  that  time  it  had  been  the  practice 
to  keep  the  flier  at  it  until  he  broke.  His  breaking  was  signalized 
sometimes  by  simple  failure  to  return  from  behind  the  enemy  lines; 
sometimes  by  becoming  mentally  and  nervously  so  exhausted  as  to 
be  of  absolutely  no  use ;  at  other  times  becoming  so  physically  worn 
out  that  even  the  casual  observer  would  recognize  his  unfitness  for 
service. 

The  old  method  was  to  get  as  much  out  of  a  flier  as  possible,  then 
discard  him  as  useless  for  further  air  service.  The  alumni  of  this 
old  school,  although  not  all  present,  because  of  the  graduation  of 
so  many  behind  the  enemy  lines,  are  now  represented  by  the  hun- 
dreds of  "  washed  out "  fliers  from  the  Italian,  French,  and  British 
services  that  one  meets  in  various  ground  activities  in  the  flying 
schools  of  America  and  Europe. 

Many  of  these  are  unnecessarily  wasted.  Their  loss  to  active  serv- 
ice could  have  been  materially  reduced  by  means  of  competent  medi- 
cal officers  who,  recognizing  the  early  beginnings  of  deterioration, 

29 


30  AIR  SEBVICE  MEDICAL. 

could  have  taken  them  off  in  time  to  permit  full  recuperation  and 
restoration  to  active  flying. 

It  is  easy  to  sum  up  the  various  means  by  which  a  flier's  usefulness 
may  be  terminated.    They  are  exactly  three: 

(1)  The  Hun. 

(2)  Failure  of  the  engine  or  plane. 

(3)  Failure  of  the  flier  himself. 

While  it  is  not  possible  to  arrive  at  exact  percentages,  estimates 
based  upon  information  from  every  source  in  Italy,  France,  and 
Great  Britain,  interviews  with  commanding  officers  and  medical  ex- 
perts in  all  the  flying  centers  and  at  the  various  fronts,  indicate  that 
not  2  per  cent  of  the  fliers  lost  to  active  service  are  put  out  by  the 
Hun.  Failures  of  the  airship  are,  at  the  present  time,  responsible  for 
very  limited  losses  to  the  service,  thanks  to  the  inspections  to  which 
they  are  constantly  subjected.  Two  years  ago  this  statement  would 
not  have  been  true;  the  mechanical  genius  of  the  world  has  been 
applied  to  make  the  airplane  safer  and  with  such  effect  that  it  hap- 
pens only  rarely  that  the  flier  becomes  useless  through  the  fault  of 
the  ship.  Statements  from  all  sources  agree  that  of  the  total  number 
of  fliers  permanently  out  of  flying  service,  not  over  8  per  cent  have 
been  rendered  unserviceable  because  of  mechanical  shortcomings  of 
plane  or  engine.  When  it  has  been  stated  that  2  per  cent  of  the  total 
number  of  fliers  incapacitated  for  further  air  service  are  put  out  by 
the  Hun,  and  8  per  cent  because  of  mechanical  shortcomings  of  the 
airplane,  the  remaining  90  per  cent  looms  large,  when  it  is  realized 
that  this  proportion  represents  troubles  in  the  flier  himself. 

After  assembling  all  possible  information,  subjecting  it  to  careful 
study  by  competent  experts  and  reaching  definite  conclusions,  the 
material  so  obtained  has  been  put  into  shape  for  further  training  of 
a  corps  of  medical  officers  who  have  had  opportunity  to  become 
familiar  with  the  Air  Medical  Service  by  actual  experience  in  the 
examination  of  applicants,  the  post-surgeon  work  in  flying  fields, 
and  the  reexamination  of  fliers.  This  is  the  epitome  of  the  develop- 
ment of  the  flight  surgeon  idea.  Through  such  a  corps  of  officers, 
established  in  the  various  flying  fields,  practical  application  can  be 
made  of  means  and  methods  devised  for  the  better  maintenance  of 
the  physical  efficiency  of  the  flier.  Just  as  the  Medical  Department 
of  the  Army  has  been  able  to  wipe  out  typhoid  fever,  and  made  it 
possible  to  construct  the  Panama  Canal  by  the  elimination  of  yellow 
fever,  so  the  Air  Medical  Service  is  destined  to  serve  by  prevention 
of  the  crash  rather  than  by  "  picking  up  the  pieces  "  afterwards. 

Medical  officers  of  the  various  air  services  had  observed  that  more 
than  half  of  the  injuries  sustained  in  crashes  were  caused  by  the 
aviator  striking  his  head  against  the  cowl.  It  was  suggested  that 
the  cowl  be  cut  out  so  as  to  give  8  inches  more  room  in  front.    A 


t— I 

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30a-7 


EXAMINATION   OF    FLIER. 


30a-8 


MAJ.   HITt'ircuCK  IN    PILOTS   SKAT. 


30a-9 


AIB   SERVICE   MEDICAL. 


31 


89118—19- 


DBCOYED. 


32  AIR  SERVICE   MEDICAL. 

report  just  received  from  the  Royal  Air  Force,  Canada,  states  that 
since  this  change  in  the  cowl  has  been  made  these  head  injuries  have 
been  practically  eliminated.  Another  suggestion  was  to  lash  the 
safety  belt  to  the  machine  by  a  simple  rubber  shock  absorber;  the 
same  report  states  that  since  this  has  been  done,  the  number  and 
extent  of  injuries  to  the  upper  abdomen  and  ribs  have  been  de- 
cidedly reduced.  The  problem  of  protecting  the  flier  against  the 
extreme  cold  of  high  altitudes  in  winter  was  solved  by  designing 
electrically  warmed  clothing,  thereby  enabling  him  to  continue  his 
flying  under  conditions,  which,  up  to  that  time,  had  rendered  it 
impossible.  The  problem  of  enabling  a  flier  to  withstand  the  glare 
of  reflected  sunlight  above  cloud  banks  and  to  enable  him  to  pierce 
camouflage  was  solved  by  furnishing  him  with  the  "  Noviol "  type 
of  goggles.  During  the  first  two  and  one-half  years  of  the  war  no 
attempt  was  made  to  compensate  the  flier  for  his  lack  of  sufficient 
oxygen  in  high-altitude  work.  There  is  one  British  squadron  which 
has  used  the  Dreyer  ox^^gen  apparatus  since  January,  1917;  a  recent 
report  from  the  British  front  states  that  this  squadron  has  been 
performing  six  times  the  amount* of  work  of  any  other  similar 
squadron  which  is  not  supplied  with  oxygen. 

The  above  are  examples  of  what  has  already  been  accomplished 
towards  reducing  this  "  90  per  cent ;"  many  other  methods  are  now 
being  developed.  Within  the  past  few  months  has  been  perfected 
an  apparatus  whereby  cadets  may  acquire  flying  experience  and 
training  .without  leaving  the  ground.*  This  machine  is  a  modifica- 
tion of  the  old-fashioned  universal  joint,  composed  of  three  con- 
centric rings  so  pivoted  together  as  to  permit  the  fuselage,  which  is 
pivoted  within  the  innermost  ring,  to  be  put  through  every  possible  * 
evolution  to  be  experienced  in  actual  flying.  This  apparatus  is 
practically  an  airplane  in  every  respect.  The  cadet  sits  in  the  fuse- 
lage and  by  means  of  the  joystick  and  rudder  puts  himself  through 
practically  all  the  evolutions  which  he  is  later  to  experience  in  the 
air.  An  analysis  of  the  "  crash  reports  "  has  shown  that  a  remarkably 
large  number  are  solely  due  to  a  failure  to  come  out  of  the  spinning 
nose  dive  or  tight  spiral.  The  only  reason  that  the  cadet  has  failed  to 
come  out  of  these  maneuvers  is  that  he  had  not  yet  become  accus- 
tomed to  these  unusual  movements.  These  evolutions  stimulate  the 
internal  ears  which  send  nerve-impulses  to  the  brain.  The  individual 
has  no  control  over  these  impulses;  the  only  thing  he  can  do  is  to 
learn  the  significance  of  these  impulses  by  experience.  The  problem 
is  extremely  simple.  All  that  is  needed  is  that  every  cadet  shall 
"  fly  "  the  apparatus  day  after  day  until  he  is  entirely  familiar  with 
these  new  sensations.  Any  mistake  that  he  makes  causes  him  no 
harm,  because  he  never  leaves  the  ground.    He  is  then  prepared  to 

•The  Ruggles  Orientator. 


THE  SIXTH  SENSE. 


(Diagrammatic.) 

THE  THREE  SEMICIRCULAR  TUBES  CONSTITUTE  THE 
"MOl ION-SENSING"  ORGAN. 


The  internal  ear  or  labyrintli  consists  of  a  bony  and  a  membraneous  part,  tlie  latter  contained  in  the 
former.  "The  bony  labyrinth  is  composed  of  the  vestibule,  the  semicircular  canals,  and  the  cochlea. 
These  three  canals  constitute  what  is  known  as  the  static  labyrinth.  The  bony  canals  contain  the  mem- 
branous canil,  an  I  the  membranous  canal,  in  turn,  contains  the  endolymph,  which  is  a  fluid  that 
fills  the  mcmlirancous  cam!.  This  posterior  part  of  tiie  internal  ear  is  constructed  solely  for  the  detec- 
tion of  movement,  anJ  constitutes  the  special  sense  organ  of  "motion-sensing".  Man  is  acquainted 
with  movement  through  this  organ  by  the  flowing  of  the  endolymph  within  the  canals. 


HUMAN  TEMPORAL  BONE,  NATURAL  SIZE,  INTERNAL  OR  BRAIN  SURFACE;  SHOW- 
ING INTERNAL  EAR  CONSISTING  OF  COCHLEA  (a),  THE  SUPERIOR  AND  POSTERIOR 
SEMICIRCULAR  CANALS  (b  and  c)  WHICH  HAVE  BEEN  EXPOSED  BY  REMOVING 
PORTION   OF   THE   BONE. 

(Actual  photograph.) 
32a-6 


32a.-7 


AlB   SEEVICE  MEDICAL.  33 

undertake  "  stunting  "  in  the  air.  Flying  training  by  this  "  ground 
training  flying  apparatus  "  should  be  under  the  combined  supervision 
of  the  officer  in  charge  of  flying  and  the  flight  surgeon. 

Another  method  of  educating  the  cadet  is  by  means  of  flying 
calisthenics.  By  daily  turning  and  tumbling  exercises  the  cadet, 
who  at  first  is  aAvkward  and  bewildered,  «oon  becomes  accustomed 
to  positions  and  movements  to  which  he  had  previously  been  un- 
accustomed. 

When  we  remember  that  each  aviator  overseas  means  an  expendi- 
ture of  upwards  of  $40,000 — as  represented  by  his  training  in  the 
ground  school  and  in  the  flying  school,  by  the  employment  of  air- 
planes and  the  necessary  mechanicians  for  their  upkeep,  as  well  as 
his  personal  expense  to  the  Government  for  pay  and  transportation — 
we  realize  that,  apart  from  the  humanitarian  standpoint,  there  is  a 
purely  military  aspect  which  demands  proper  care  of  this  tremendous 
financial  investment.  This  saving  of  invaluable  human  material 
and  money  can  be  accomplished  only  by  providing  a  specially 
trained  medical  officer  who,  as  medical  advisor  to  the  Commanding 
Officer,  is  charged  with  the  duty  of  maintaining  the  mental  and 
physical  fitness  of  the  individual  fliers  of  the  command.  This  officer 
is  the  Flight  Surgeon. 

To  meet  this  problem,  the  general  staff  authorized  this  new  grade 
in  the  tables  of  organization,  the  "  Flight  Surgeon."  Authorization 
was  also  made  for  the  grade  of  "  Physical  Director."  The  original 
authorization  provided  for  50  flight  surgeons  and  50  physical  direc- 
tors; one  flight  surgeon,  with  a  physical  director  as  his  assistant,  was 
to  be  provided  for  each  flying  school  in  the  United  States,  and  the 
others  for  overseas  service  as  needed. 

Specifically,  "  the  duty  of  the  Flight  Surgeon  is  to  act  as  advisor 
to  the  Commanding  Officer  of  flying  schools  and  squadron  groups. 
Although  under  the  Post  Surgeon,  he  has  freedom  of  independent 
initiative  in  all  questions  of  flying  fitness  of  aviators  or  cadets.  Sub- 
ject to  the  approval  of  the  Commanding  Officer,  he  is  expected  to  in- 
stitute such  measures  as  periods  of  rest,  recreation,  and  temporary  ex- 
cuse from  duty,  as  may  seem  to  him  advisable.  He  takes  sick  call 
for  aviators  and  cadets  and  recommends  the  disposition  of  cases 
excused  from  duty.  He  will  visit  such  cases  as  may  be  in  the  hospital 
at  the  post  and  consult  with  the  attending  surgeon  or  physician 
regarding  them.  From  time  to  time  he  will  make  routine  reexamina- 
tions of  aviators  and  cadets;  also  such  special  examinations  as  he 
may  deem  advisable,  being  assisted  therein  by  data  furnished  by  the 
Branch  Medical  Research  Laboratory.  He  will  live  in  as  close  touch 
with  the  fliers  and  cadets  at  his  station  as  is  consistent  with  th« 
conditions." 


34  AIE  SERVICE   MEDICAL. 

"  Each  Flight  Surgeon  will  have  as  an  assistant  a  Physical  Director, 
whose  duty  is  to  supervise  such  recreation  and  physical  training  of 
aviators  and  cadets  as  is  considered  necessary.  He  will  live  and  mess 
with  the  cadets,  keep  as  closely  in  touch  with  them  as  possible,  study 
their  habits,  temperaments,  and  physical  fitness,  and  advise  the 
Flight  Surgeon  in  all  matters  regarding  these  points." 

So  much  for  the  official  routine ;  it  needs  but  a  glance  at  the  many 
activities  suggested  to  realize  that  back  of  this  order  was  a  great 
need — the  daily  care  and  watchfulness  over  the  aviator. 

The  medical  study  of  aviation  is  so  new  that  unless  a  medical 
officer  has  been  specially  trained  for  the  aviation  service  he  can  have 
no  idea  whatever  of  the  methods  of  making  diagnosis  of  the  ills 
peculiar  to  flying.  For  this  highly  specialized  phase  of  medical 
work  the  Flight  Surgeon  must  have  certain  special  qualifications. 
For  this  reason  the  greatest  care  has  been  exercised  in  the  selection  of 
each  Flight  Surgeon,  as  it  was  recognized  that  the  entire  success  of  the 
work  depended  upon  the  personality,  experience,  and  diagnostic  skill 
of  the  medical  officers  selected  for  this  special  duty. 

Ideal  material  for  Flight  Surgeons  became  available  when  a  large^ 
number  of  Physical  Examining  Units  completed  their  work.  Those 
medical  officers  were  chosen  who  had  had  large  experience  in  examin- 
ing hundreds  or  thousands  of  applicants  for  the  service.  From  this 
group  were  selected  those  whose  personality  was  such  that  they  could 
not  only  command  the  respect  but  the  confidence  of  the  individual 
aviator.  This  is  essential.  The  efficient  Flight  Surgeon  is  one  whose 
personality  is  such  that  the  cadet,  flying  officer,  or  aviator  at  the 
front,  feels  that  he  has,  in  his  Flight  Surgeon,  one  to  whom  he  can  go 
without  restriction — in  the  same  spirit  with  which,  in  civilian  life, 
he  was  accustomed  to  consult  his  family  physician.  When  a  prospec- 
tive Flight  Surgeon  had  been  selected  for  his  exceptional  ability  and 
knowledge  of  the  special  diagnostic  tests,  and  for  his  personality,  he 
was  then  sent  to  the  Medical  Research  Laboratory  at  Mineola,  Long 
Island,  where  he  received  intensive  training  in  those  special  tests  with 
which  he  had  not  yet  become  familiar  in  his  original  examining 

work. 

The  Flight  Surgeon  was  also  given  adequate  opportunity  to  acquire 
actual  flying  experience  both  at  Mineola  and  at  the  flying  fields. 
This  enabled  him  to  supplement  his  other  special  preparations  for 
his  own  peculiar  work  with  the  much  needed  first-hand  "  knowledge 
of  the  air."  Permission  has  been  granted  by  the  Director  of  Military 
Aeronautics  for  these  officers,  among  others,  to  take  regular  ground 
and  air  courses  of  instruction  in  flying,  and  many  of  the  Flight  Sur- 
geons have  already  qualified  for  R.  M.  A.  Actual  flying  is  of  great 
value  as  an  additional  aid  in  rendering  the  Flight  Surgeon  better  able 


Ph 

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02 

< 

P^ 
CO 

O 

W 


34ar-l 


34a-2 


34a-3 


o 

o 


34a-4 


-ffl 


34a-d 


POOL. 


34a-6 


BOWLING. 


i 


34a-7 


MAJ.  \VM.  R.  REAM,  THE  FIRST  FLIGHT  SURGEON 
TO  BE  PUT  ON  FLYING  STATUS. 


MAJ.    REAM   IN   HIS   PLANE. 


34a-S 


AIR   SERVICE   MEDICAL.  36 

to  realize  and  cope  with  the  peculiar  conditions  and  ills  incidental 
to  aviation. 

At  the  Medical  Research  Laboratory  he  was  enabled  to  secure  all 
the  up-to-the-minute  information  regarding  the  eye,  ear,  nose  and 
throat,  cardio-vascular,  physiologic,  psychiatric,  and  psychologic 
work.  Of  the  new  problems  taken  up  at  the  Medical  Research  Lab- 
oratory, studies  in  psychiatry  were  of  peculiar  importance.  No  Flight 
Surgeon  can  adequately  diagnose  an  aviator's  condition  who  has  not 
the  ability  to  determine  the  mental  condition  of  the  individual.  If 
an  aviator  is  having  sleepless  nights,  worrying  over  financial  problems, 
anxieties  regarding  the  wife  at  home  w'ho  is  about  to  become  a  mother, 
or  other  anxieties  of  everyday  occurrence  in  human  life,  it  is  not  sur- 
prising if  we  find  that  he  is  not  in  fit  condition  to  fly.  It  has  been 
repeatedly  proven  that  if  the  aviator  who  has  been  flying  badly  under 
such  a  mental  handicap,  tells  his  troubles  to  an  intelligent  and  sympa- 
thetic listener,  he  is  almost  invariably  able  to  '•  get  hold  of  himself," 
after  which  he  goes  out  again  and  flies  well.  The  Medical  Research 
Laboratory  provides  instruction  in  all  these  essential  branches;  after 
a  course  of  four  or  five  weeks  of  such  intensive  instructions  the  Flight 
Surgeon  is  then  sent  to  work  among  the  aviators,  under  actual  service 
conditions. 

It  has  become  evideiit  during  the  past  nine  months  through  activi- 
ties of  nutritional  surVey  parties  of  the  Food  Division,  Surgeon  Gen- 
eral's Office,  that  there  is  great  need  in  each  aviation  camp  for  a 
Nutrition  Officer.  Stated  in  the  briefest  terms  the  needs  for  his  serv- 
ices are  these : 

The  strain  on  the  flier — especially  the  mental  strain — is  great. 
He  is  very  susceptible  while  on  flying  duty  to  influences  that  would 
ordinarily  not  affect  him  at  all.  To  reach  and  maintain  his  maximum 
efficiency  requires  his  being  in  the  best  physical  and  mental  condition. 
In  peace  times,  under  conditions  where  neither  life  and  death  nor 
great  ideals  are  at  stake,  a  "  training  table  "  is  maintained  for  club 
or  college  athletes.  This  is  done  because  it  is  recog-nized  that  im- 
proper feeding  may  reduce  a  man's  efficiency,  or  even  put  him  "  out  of 
the  running"  in  a  contest  in  which  his  best  is  required  to  win.  In 
the  case  of  the  flier  we  are  concerned,  when  he  goes  up,  not  only  with 
questions  of  life  and  death  and  ideals,  but  with  the  fact  that  he,  more 
than  the  average  athlete,  depends  for  success  upon  clearness  of  mind, 
quickness  of  thought,  keenness  of  judgment.  All  these  are  mental 
faculties,  not  muscular.  The  nei'vous  system  is  more  highly  diflPer- 
entiated  than  the  muscular  system,  and  bj^  reason  of  that  fact  more 
easily  upset  by  improper  food. 

For  the  highest  efficiency  of  the  flier  there  is  required  some  form 
of  training  table.  At  times  when  he  is  slightly  unfit,  with  headache, 
constipation,  etc.,  this  is  doubly  needed.    A  Nutrition  Officer  with 


36  AIR  SEEVICE  MEDICAL. 

special  training  in  knowledge  of  food  values  should  supervise  the 
messes  of  all  students  and  oflScer  fliers  in  order  to  keep  up  the  effi- 
ciency of  the  fliers  and  prevent  as  far  as  possible  the  development 
of  digestive  ailments  of  even  minor  character.  But  in  addition  to 
this,  every  flier  who  develops  a  digestive  disorder  should  constitute 
a  special  problem  for  the  Nutrition  Officer  so  that  he  may  become 
"  fit  "  again  at  the  earliest  possible  moment.  With  such  food  super- 
vision the  general  efficiency  of  the  fliers  can  be  raised  definitely,  the 
number  of  hours  per  month  that  these  men  are  fit  for  flying  duty 
increased,  and  finally  the  danger  to  both  life  and  equipment  of  the 
flier  greatly  reduced. 

With  expert  supervision  of  the  flier's  nutrition  and  exercise,  sup- 
plementing his  own  professional  knowledge  concerning  flying  and 
the  aviator,  tlie  Flight  Surgeon  neglects  nothing  of  a  practical  value 
which  can  be  used  in  maintaining  in  the  highest  degree  the  physical 
efficiency  of  the  Air  Fighting  Force. 

Without  exception  the  Commanding  Officers  of  the  aviation  fields 
have  welcomed  the  advent  of  the  Flight  Surgeon.  They  realize  the 
tremendous  responsibility  of  sending  a  man  into  the  air  who  may, 
at  the  time,  be  mentally  or  physically  unfit  for  flying.  No  Command- 
ing Officer  has,  for  the  sake  of  a  large  record,  ever  shoAvn  a  tendency 
to  force  his  men  into  the  air.  From  a  military  standpoint  they  re- 
alize that  an  attempt  to  escape  duty  on  the  part  of  an  aviator  is  an 
altogether  different  matter  from  such  an  attempt  of  men  enlisted  in 
other  branches  of  the  service.  The  Commanding  Officer,  or  officers 
in  charge  of  flying,  who  are  constantly  observing  their  men  in  flight, 
sense  certain  transitory  changes  in  a  man's  condition  which  impair 
his  air  efficiency.  They  are  often  called  upon  to  ground  such  a  man 
or  relieve  him  from  duty.  It  is  not  to  be  wondered  at,  therefore, 
that  they  welcome  the  support  of  the  Flight  Surgeon  who  adds  a 
medical  knowledge  to  their  own,  which  after  all  is  based  upon  ex- 
perience alone.  The  Flight  Surgeon,  in  addition  to  maintaining  at 
the  highest  point  the  physical  efficiency  of  the  flying  force  of  a 
command,  is  prepared  at  any  time  to  furnish  to  the  Commanding  Offi- 
cer a  reliable  expert  opinion  as  to  each  individual's  mental  and  physi- 
cal fitness  for  flying  duty. 


3Ca 


PART|II. 

» 

CHAPTER  I. 
THE  ORGANIZATION  FOR  EXAMINATION  OF  APPLICANTS. 


Owing  to  the  enormous  number  of  applicants  for  the  Air  Service 
to  be  examined  in  a  relatively  short  period  it  became  apparent  that 
a  radical  departure  from  precedent  would  have  to  be  made  in  order 
to  handle  this  number  effectively.  During  the  early  part  of  1917 
the  Aviation  Examining  Board  in  Washington,  D.  C.,  passed  on  ap- 
proximately all  applicants  for  commissions  in  the  Aviation  Section. 
Signal  Corps:  but  as  it  became  apparent  that  the  commissioned 
personnel  would  be  greatly'  augmented,  the  number  of  these  boards 
was  increased,  until  in  January,  1918,  there  were  35  Examining 
Boards  established  in  the  principal  cities  of  the  United  States,  which, 
with  the  32  additional  boards  established  at  National  Army  and 
National  Guard  divisional  cantonments,  made  a  total  of  67  Aviation 
Examining  Boards. 

Although  the  type  of  Examining  Board  oflicially  prescribed  was 
adhered  to,  the  details  of  the  constitution  of  the  board  were  altered 
in  order  to  facilitate  the  handling  of  such  large  numbers  of  appli- 
cants. Each  board  had  a  president,  a  representative  of  the  Air 
Service,  and  a  medical  officer. 

These  representatives  of  the  Air  Service  were  responsible  for 
determining  the  mental,  educational,  professional,  and  moral  de- 
sirability of  the  applicants  selected.  As  this  work  was  of  a  highly 
specialized  nature,  these  men  were  called  upon  to  undergo  intensive 
special  training  as  expert  examiners  for  this  particular  service.  It 
was  also  necessary  that  the  medical  member  of  the  board  should  be 
thoroughly  qualified  to  make  examinations  in  ophthalmology,  oto- 
laryngology, the  cardio-vascular  system,  the  respiratory  system,  and 
neurology. 

To  meet  the  demands  for  examination  in  various  localities,  and 
because  it  is  manifestly  impossible  to  find  highly  developed  special 
training  in  any  one  individual  along  all  of  the  above-mentioned  lines, 
the  medical  member  of  the  board  was  elaborated  into  the  Physical 
Examining  Unit,  the  size  of  the  unit  depending  on  the  amount  of 
applicant  material  assembled  at  any  one  place.     In  some  cases  as 

37 


38  AIK   SERVICE  MEDICAL. 

many  as  four  or  five  board  examiners  were  working;  at  the  same 
time  the  number  of  physicians  working  together  as  a  Physical 
Examining  Unit  varied  at  different  points  from  7  to  28. 

The  necessity  for  a  special  system  of  keeping  the  records  was  met 
by  devising  certain  standardized  paper-work  blanks  which  enabled 
the  Examining  Unit  to  file  complete  records  of  its  findings  in  every 
case,  together  with  a  file  of  cross-index  records  completing  the  men- 
tal, moral  and  professional  findings.  In  this  way  the  Examining 
Board's  and  Physical  Examining  Units  attained  a  proficiency  which 
permitted  the  examination  of  a  large  number  of  applicants  per  day 
at  each  place.  As  a  matter  of  fact,  a  greater  number  of  individuals 
consulted  the  Board  than  eventually  applied,  for  it  became  apparent 
very  early  that  one  of  the  important  functions  which  the  Examining 
Board  could  subserve  was  the  dissuasion  from  applying  of  all  those 
Avho  were  manifestly  the  wrong  kind  of  material.  The  use  of  mature 
judgment  on  the  part  of  the  Examining  Board  in  culling  from  ap- 
plicant material  that  which  was  unsatisfactory  at  a  preliminary  con- 
sultation resulted  in  a  great  saving  of  time  on  the  part  of  the 
Physical  Examining  Units. 

In  the  course  of  a  few  months  the  men  who  were  conducting  the 
work  of  the  Examining  Boards  had  acquired  a  technique  in  the  con- 
duct of  the  examinations  which,  while  individually  developed,  was 
surprisingly  similar  in  general  character.  Most  examiners  were  able 
to  complete  between  four  and  five  examinations  per  hour,  but  this 
came  to  be  regarded  as  the  maximum  of  speed.  Whereas  it  was 
obviously  impossible  to  establish  in  the  67  boards,  which  were  op- 
erating at  the  same  time,  anything  like  an  absolute  model  for  basing 
judgment  as  to  the  qualifications  of  an  applicant,  the  standard  main- 
tained was  sufficiently  high  to  supply  the  ground  schools  with  satis- 
factory material. 

The  professional  or  mental  examination  requires  the  utmost  judg- 
ment and  knowledge  of  men.  Not  every  man  is  at  his  best  when 
confronted  with  the  immediate  necessity  of  displaying  his  mental 
ability.  Extreme  sensitiveness  or  modesty  may  put  him  at  a  dis- 
advantage, his  alertness  being  temporarily  obscured;  and  it  is  here 
that  the  examiner  can  display  the  tact  that  will  bring  into  notice 
any  desirable  qualities  which  the  applicant  may  have. 

It  became  apparent  in  the  conduct  of  these  board  examinations 
that  it  was  quite  important  to  take  into  consideration  the  existence 
of  qualifications  in  applicants  whose  early  educational  training  had 
been  neglected  by  cause  of  circumstances.  This  is  well  illustrated  by 
the  following  instance :  A  first  glance  over  the  blanks  of  two  appli- 
cants showed  one  of  them  to  be  a  plumber,  the  other  to  be  a  graduate 
of  a  well-known  university.  The  Board  President  called  attention 
to  the  probability  that  the  first  would  evidently  prove  unsuitable  for 


AIB  SEBVICE  MEDICAL.  39 

officer  material,  whereas  the  second  undoubtedly  would  prove  to  be 
a  man  of  culture  and  education,  with  a  reasonable  amount  of  sports 
and  athletic  experience.  The  applicants  were  then  called  upon  to 
enter  and  be  examined.  The  first  appeared,  and  apparently  was  a 
very  unusual  type  of  plumber.  As  the  examination  proceeded  the 
questions  of  the  President  of  the  Board  eUcited  the  facts  that  while 
the  applicant  followed  plumbing  as  a  breadwinning  occupation,  he 
had  diligently  pursued  a  course  of  self-education  and  had  attained 
an  unusually  high  familiarity  with  radio  work.  In  fact,  he  had 
established  a  radio  laboratory  in  connection  with  his  plumbing  shop, 
in  which  he  devoted  a  great  deal  of  his  unoccupied  time  to  the  de- 
velopment of  this  particular  hobby,  and  his  proficiency  in  this  had 
reached  a  point  which  earned  the  recognition  of  the  faculty  of  a 
near-by  college.  Some  of  the  students  at  this  college  applyingJor  a 
course  in  radio  work  had  been  organized  into  a  special  class  By  the 
faculty  and  had  been  turned  over  to  the  plumber  for  instruction. 
This  proved  so  successful  that  further  classes  in  radio  work  were 
organized  among  students  of  this  institution  of  learning.  In  addi- 
tion, the  plumber  turned  out  to  be  a  man  of  broad  views  and  capa- 
bilities, and  was  unanimously  adjudged  as  extremely  desirable  ma- 
terial for  officer  training  in  the  Air  Service.  The  university  graduate 
was  then  called  in  for  examination,  and  it  was  immediately  evident 
that  he  was  the  type  of  perfunctory  student  who  had  done  just 
enough  work  in  the  required  course  to  enable  him  to  qualify  for  his 
degree.  He  had  taken  no  part  in  athletics  of  any  kind,  and  his  record 
of  achievement  both  in  college  and  afterwards  was  only  a  drab 
blank.  In  this  case  it  was  again  the  unanimous  opinion  of  the  Board 
that  he  was  distinctly  not  desirable  for  officer  material  for  the  Air 
Service. 

In  testing  the  general  fitness  of  an  applicant,  the  questions  asked 
are  of  broad  scope,  aimed  to  suit  the  individual  case,  but  obviously 
they  would  defeat  their  own  purpose  if  designed  to  trip  a  man, 
make  him  ill  at  ease,  or  in  any  way  put  him  at  a  disadvantage. 

Final  decision  of  the  Examining  Board  as  to  the  acceptability  of 
the  individual  applicant  was  made  after  receiving  the  complete  medi- 
cal report  from  the  Physical  Examining  Unit. 


% 


CHAPTER  IL, 
THE  ESTABLISHING  OF  67  PHYSICAL  EXAMINING  UNITS. 


Through  our  entrance  into  the  world  war,  it  was  found  necessary 
to  devise  at  once  a  practical  means  of  enlarging  the  Air  Service 
commensurately  with  the  role  it  was  destined  to  play  in  our  military 
operations.  There  was  an  immediate  demand  for  tliousands  of  men 
who  would  measure  up  to  the  physical  and  mental  requirements  for 
aviation. 

The  Surgeon  General  of  the  United  States  Army,  faced  with  this 
problem,  decided  to  place  the  supervision  of  the  work  in  the  hands 
of  one  medical  officer,  giving  him  full  power,  under  the  Chief  Signal 
Officer,  to  determine  the  physical  fitness  of  these  applicants. 

The  order  which  created  this  work  of  such  far-reaching  impor- 
tance should  be  here  quoted: 

Special  Orders,  Wak  Department, 

No.  207.  WasJdngton,  September  6,  1911. 

Lieut.  Col.  Tlieodore  C.  Lystor.  IMedical  Corps,  now  on  duty  in  the  offi«'e 
of  the  Surgeon  General,  in  addition  to  his  other  duties,  is  designated  as  Chief 
Surgeon,  Aviation  Section,  Signal  Corps,  United  States  Army. 

Lieut.  Col.  George  H.  Crabtree,  United  States  Army,  retired,  now  on  duty 
in  the  office  of  the  Surgeon  General,  will  report  in  person  to  the  Chief  Signal 
Officer  of  the  Army  for  duty  as  assistant  to  the  Chief  Surgeon  and  Sanitary 
Inspector,  Aviation  Section,  Signal  Corps,  United  States  Army. 

By  order  of  the  Secretary  of  War  : 

Tasker  H.  Bliss, 

Major  General,  Chief  of  Staff. 
Official : 

H.  P.  McCain, 

The  Adjutant  General. 

The  physical  examinations  required  new  methods;  the  physical 
qualifications  new  standards.  These,  also,  had  to  be  designed  not 
merely  for  one  place  or  one  examining  group. 

For  this  purpose  a  medical  officer  was  sent  to  each  of  35  cities 

throughout  the  United  States  to  assist  in  establishing  at  these  centers 

medical  units  for  the  examination  of  applicants  for  aviation;  also, 

by  public  meetings  not  only  to  explain  the  true  nature  of  this  new 

branch   of  the   service,   but  to   correct   any   erroneous   impression 

regarding  the  rigidity  of  the  tests. 

41 


42  AIE   SERVICE   MEDICAL. 

These  public  meetings  were  attended  by  the  mediral  profession  and 
general  public,  who  were  instructed  in  the  great  need  for  large 
numbers  of  fliers,  in  the  desirability  of  this  service,  and  in  the 
detailed  requirements  for  admission. 

On  the  day  following  the  general  public  meeting  there  was  held  a 
special  meeting  of  certain  physicians  of  the  city.  It  was  at  this 
meeting  that  the  Physical  Examining  Unit  was  established.  One 
of  the  physicians  was  selected  to  be  commissioned  in  the  Medical 
Reserve  Corps  and  placed  in  charge  of  the  unit.  The  personnel  of 
the  civilian  consultants  was  carefull}'  selected  and  organized  into 
groups  representing  their  respective  specialties. 

Every  minute  detail  of  the  physical  examination  blank  (Form  609 
A.  G.  O.)  was  then  explained  and  discussed.  It  was  emphasized 
that  the  service  reqtiired  that  each  miit  should  conform  to  certain 
definite  standards.  The  identical  instruments  of  precision,  such 
as  the  phorometer,  Jennings  color  test,  and  the  American  modifi- 
cation of  the  Barany  chair,  were  required  in  each  unit. 

Acknowledgment  is  made  here  of  the  spirit  and  enthusiasm  with 
which  these  groups  of  physicians  entered  into  the  attempts  to  ac- 
complish a  work  of  a  standard  character. 

Hospitals  and  other  already  existing  institutions  with  their  equip- 
ment were  used  for  these  examining  centers.  The  consultants  chosen 
"were  well-recognized  eye,  ear,  nose  and  throat  specialists,  internists, 
surgeons,  and  neurologists.  Their  work  was  diAnded  into  three 
groups,  (1)  the  eye,  (2)  the  ear,  nose  and  throat,  and  (3)  the  general 
physical  examination. 

Each  Physical  Examining  Unit  was  authorized  to  select  a  man  to 
act  as  clerk,  sending  his  name  to  the  Office  of  the  Chief  Surgeon, 
which  then  authorized  this  man's  enlistment  in  the  grade  of  a 
private.  Medical  Department,  and  assigned  him  for  duty  with  the 
unit.  This  being  accomplished,  recommendation  was  at  once  made 
for  his  promotion  to  the  grade  of  sergeant,  if  such  promotion  seemed 
advisable.  In  many  places  where  large  numbers  were  examined 
volunteer  assistants  were  obtained,  with  the  sergeant  supervising 
their  work. 

These  units  determined  the  physical  condition  of  the  men  ordered 
by  the  Examining  Board  to  appear  for  such  examination.  "V^^ien 
the  examination  had  been  completed,  the  papers  were  signed  by 
the  officer  in  charge  of  the  unit  and  returned  to  the  Board,  which 
body  then  considered  the  man's  mental  and  moral  make-up,  de- 
cided as  to  his  fitness,  and  announced  to  him  the  result.  If  he  was 
accepted  he  was  immediately  enlisted  in  the  Reserve  Corps  and 
placed  on  the  inactive  list. 

The  first  unit  was  established  in  Philadelphia,  at  the  hospital  of 
the  University  of  Pennsylvania,  where  the  aviation  examinations 


AIE  SEEVICE  MEDICAL.  43 

were  begun  on  May  15,  1917.  After  this,  units  were  established  with 
great  rapidity  in  New  York,  Boston,  Ithaca,  Washington,  and  Chi- 
cago, all  of  these  being  in  active  operation  by  the  end  of  June  of 
that  year. 

On  July  6,  1917  (Special  Order  No.  155,  paragraph  35),  a  medical 
officer  was  detailed  to  visit  the  following  places  to  establish  Physical 
Examining  Units  and  to  standardize  the  examinations:  Champaign, 
111.;  Indianapolis,  Ind. :  St.  Louis,  Mo.:  Kansas  City,  Mo.;  Denver, 
Colo.;  Memphis,  Tenn. ;  Cincinnati,  Ohio;  Cleveland,  Ohio;  Buffalo, 
N.  Y. ;  Pittsburgh,  Pa.    This  entire  tour  was  concluded  in  six  weeks. 

More  units  were  established  in  the  fall  of  1917.  The  following 
itinerary,  showing  as  it  does  the  rapidity  with  which  ground  was 
covered,  emphasized  the  enthusiastic  cooperation  of  the  medical 
profession  in  each  city,  which  made  it  possible  to  establish  so  many 
units  in  such  a  short  time : 

•     1917. 

Leave  Washington Sept.  6. 

Arrive  Richmond,  Va Sept.  6. 

General  public  meeting  under  auspices  medical  societies, 

Friday  evening.  Sept.  7. 

Leave  Richmond Sept.  8. 

Arrive  Charleston,  S.  C Sept.  9. 

General  public  meeting Monday  evening,  Sept.  10. 

Leave  Charleston , Sept.  11. 

Arrive  Savannah,  Ga Sept.  11. 

General  public  meeting Wednesday  evening,  Sept.  12. 

Leave  Savannah Sept.  13. 

Arrive  Atlanta,  Ga Sept.  14. 

General  public  meeting Friday  evening,  Sept.  14. 

Leave  Atlanta Sept.  15. 

Arrive  Birmingham,  Ala Sept.  16. 

General  public  meeting Monday  evening,  Sept.  17. 

Leave    Birmingham Sept.  18. 

Arrive  New  Orleans,  La Sept.  18. 

General  public  meeting Wednesday  evening,  Sept.  19. 

Leave  New  Orleans Sept.  20. 

Arrive  San  Antonio,  Tex Sept.  24. 

General  public  meeting Wednesday  evening,  Sept.  26. 

Leave  San  Antonio Sept.  27. 

Arrive  Los  Angeles,  Cal Sept.  30. 

General  public  meeting Monday  evening,  Oct.  1. 

Leave  Los  Angeles Oct.  4. 

Arrive  San  Francisco,  Cal Oct.  6. 

General  public  meeting Saturday  evening,  Oct.  7. 

These  urban  units  were  supplemented  by  the  addition  of  32  units 
at  divisional  cantonments,  and  so  successful  was  this  method  of 
handling  this  great  bulk  of  work  that  by  the  fall  of  1917,  67  units 
were  actively  conducting  the  examinations.  The  following  list  of 
Physical  Examining  Units  and  Examining  Boards  includes  the  names 


44  AIR  SERVICE  MEDICAL. 

of  the  officers  in  charge,  civilian  consultants  and  volunteer  clerks, 
representing  the  complete  personnel  of  the  units.  This  list  gives 
some  idea  of  the  work  involved  in  the  service  of  "  The  selection  of 
the  aviator." 

PHYSICAL  EXAMINING   UNITS  WITH   EXAMINING   BOARDS 

ATTACHED. 

Alexandria,  La. — Base  Hospital,  Camp  Beauregard. 

Officer  in  charge,  Capt.  H.  H.  Forcheimer,  M.  R.  C.    Capt.  James  C.  Har- 

kinns,  M.  R.  C. ;  Capt.  Robert  Lockhart,  M.  R.  C. 
Examiuiug   board :    President,    Division    Signal    Officer ;    IJeut.    James    H. 
Phillips,  M.  R.  C. 
American  Lake,  Wash. — Base  Hospital,  Camp  Leivis. 

Officer  in  charge,  Maj.  J.  J.  Kyle,  M.  R.  C. ;  Capt.  R.  K.  Hutchins,  M.  R.  C. ; 

Capt.  David  C.  Twitchell,  M.  R.  C. ;  Lieut.  William  J.  Kerr,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;   Lieut.  Timothy  T. 
Gibson,  M.  R.  C. 
Annapolis  Junction,  Md. — Base  Hospital,  Camp  Meade. 

Officer  in  charge,  Blaj.  E.  C.  Ellett,  M.  R.  C.    Maj.  George  B.  Wood,  M.  R. 

C. ;  Capt.  Gordon  Wilson,  M.  R.  C. ;  Lieut.  A.  E.  Strauss,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Lee  A.  Hadley, 
M.  R.  C. 
Anniston,  Ala. — Base  Hospital,  Camp  McClellan. 

Officer  in  charge,  Capt.  A.  L.  Bishop,  M.  R.  C. ;  Capt.  Harold  D.  Brewster, 

M.  R.  C. ;  Capt.  W.  W.  Osgood,  M.  R.  C ;  Lieut.  Ernest  P.  Boas,  M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer ;•  Lieut.  Adlai  E.  Calla- 
han, M.  R.  C. 
Atlanta,  Gk. — Base  Hospital,  Camp  Gordon. 

Officer  in  charge,  Capt.  Cabot  Lull,  M.  R.  C. ;  Capt.  L.  H.  Prince,  M.  R.  C. ; 

Lieut.  G.  A.  Bulson,  M.  R.  C. ;  Lieut.  C.  D.  Giddings,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Otto  J.  Schott, 
M.  R.  C. 
Atlanta,  Ga. — Emory  University. 

Officer  in  charge,  Capt.  Dunbar  Roy,  M.  R.  C. ;  Capt.  Louis  Levy,  M.  R.  C. ; 

Lieut.  Ernest  S.  Colvin,  M.  R.  C. 
Examining  board :  President,  Capt.  I.  H.  Saunders,  S.  C.    First  Lieut.  John 
H.  Hall,  M.  R.  C. 

Eye,  ear,  nose  and  throat :  Dr.  G.  D.  Ayer. 

General  physical :  Dr.  C.  C.  Aven,  Dr.  W.  L.  Funkhouser,  Dr.  \j.   G. 
Baggett,  Dr.  W.  W.  Young,  Dr.  R.  A.  Bartholomew,  Dr.  John  H. 
Vermilye. 
Augusta,  Ga. — Base  Hospital,  Camp  Hancock. 

Officer  in  charge,  Maj.  J.  F.  Gulp,  M.  R.  C. ;  Capt.  Charles  H  Erway,  M.  R. 

C. ;  Capt.  W.  J.  Olds,  M.  R.  C. ;  Lieut.  S.  Calvin  Smith,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Alex.  A.  Drill, 
M.  R.  C.  .  - 

Austin,  Tex. 

Officer  in  charge,  Capt.  John  H.  Timberman,  M.  R.  C. 

Eye,  ear,  nose  and  throat:  Dr.  S.  N.  Key,  Dr.  S.  J.  Clarke,  Dr.  J.  R. 

Nicholls,  Dr.  H.  L.  Hilgartner,  Dr.  W.  A.  Harper. 
General  physical :  Dr.  T.  J.  Bennett,  Dr.  S.  B.  Hudson. 


AIR  SERVICE  MEDICAL.  45 

Ayer,  Mass. — Base  Hospital,  Camp  Devens. 

Officer  ill  charge,  Maj.  W.  F.  Kuowles,  M.  R.  C. ;  Maj.  \V.  B.  Lancaster,  M. 

R.  C. ;  Capt.  H.  W.  Stevens,  M.  R.  C. ;  C.  S.  Harry  I.  Barnes,  U.  S.  A. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Richard  J.  R. 
Caines,  M.  R.  C. 
Battle  Crkek,  Mich. — Brific  Hospital,  Camp  Custer. 

Officer  in  charge,  Jlaj.  R.  B.  Canfield,  M.  R.  C. ;  Maj.  G.  F.  Suker,  M.  R.  C. ; 

Lieut.  M.  K.  Fromm,  M.  R.  C. ;  Lieut.  A.  .F.  Jennings,  M.  R.  C. 
Examining   board:    President.    Division    Signal    Officer;    Capt.    William    J. 
Uppendahl,  M.  R.  C. 
BiKMiNGHAM,  Ala. — University  Free  Dispensary. 

Officer  in  charge,  Capt.  Kosciusko  W.  Constantine,  M.  R.  C. 
Examining  board :  Lieut.  Gaston  W.  Rogers,  M.  R.  C. 
Eye :  Dr.  S.  L.  Ledbetter,  sr. ;  Dr.  A.  B.  Harris. 
Ear :  Dr.  W.  B.  Smith,  Dr  G.  W.  Harrison. 

General  Physical:  Dr.  H.   S.  Ward,  Dr.  U.  .T.  W.  Peters.  Dr.  E.  M. 
Mason. 
Boston,  Mass. — Massachusetts  Charitable  Eye  and  Ear  Infirmary. 

Officer  in  charge,  Capt.  Harry  P.  Cahill,  M.  R.  C. ;  Lieut.  John  G.  Jennings, 

M.  R.  C. 
Examining  board  No.  1 :  President,  Capt.  F.  L.  Wells,  C.  S.    Capt.  Wm.  W. 

Laing.  M.  R.  C. ;  Lieut.  Wm.  J.  Harkins,  M.  R.  C. 
Examining  board  No.  2 :  President,  Capt.  Abraham  L.  Laviue.  S.  C.    Capt. 
Chas.  S.  Butler,  M.  R.  C. ;  Capt.  Robt.  F.  Souther,  M.  R.  C. 
Eye,  ear,  nose,  and  throat :  Dr.  William  J.  Harkins,  Dr.  Wm.  I.  Wig- 
gin,  Dr.  Geo.  H.  Poirier,  Dr.  Harold  L.  Babcock. 
General  physical :   Dr.   Martin   J.   English,   Dr.   John    O'Donnell,   Dr. 
Francis  T.  Jansen,  Dr.  .Joseph  M.  Lynch. 
Buffalo,  N.  Y. — Buffalo  General  Hospital. 

Officer  in  charge,  Capt.  George  F.  Scott,  M.  R.  C. 

Examining  boai'd :  President,  Capt.  Lester  F.  Gilbert,  S.  C.     Capt.  George 
F.  Cott,  M.  R.  C. 
Eye :  Dr.  Alfred  F.  Luhr,  Dr.  Ray  A.  Edson,  Dr.  A.  'g.  Bennett^  Dr. 
H.  H.  Glosser,  Dr.  F.  Park  Lewis,  Dr.  H.  W.  Cowper,  Dr.  Lucien 
Howe. 
Ear,  nose,  and  throat :  Dr.  Chester  C.  Cott,  Dr.  Walter  J.  Wurtz. 
General  physical :  Dr.  F.  J.  Parmenter.  Dr.  Chas.  A.  Wall,  Dr.  Jas.  B. 
Gross,   Dr.   H.   C.   Buswell.    Dr.   Henry   R.   Hopkins,   Dr.   Chas.   G. 
Stockton. 
Volunteer  clerks :  Miss  Anna  B.  O'Day. 
Canal  Zone. — Ancon  Hospital. 

Officer  in  charge :  Capt.  George  C.  Marshall,  M.  R.  C. 
Chaklotte,  N.  C. — Base  Hospital,  Camp  Greene. 

Officer  in  charge :  Capt.  George  A.  Renn,  M.  R.  C. ;  Lieut.  Herman  Elwyn, 

M.  R.  C. ;  Lieut.  T.  E.  McConnell,  M.  R.  G. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Curtis  R.  Seu- 
ter,  M.  R.  C. 
Chableston,  S.  C. — Roper  Hospital. 

Officer  in  charge :  Capt.  Chas.  W.  Kollock,  M.  R.  C. 
Examining  board :  Capt.  Chas.  W.  Kollock,  M.  R.  C. 
Eye,  ear,  nose,  and  throat :  Dr.  Charles  W.  Kollock. 
General  physical :  Dr.  J.  A.  Finger,  Dr.  J.  C.  Guess,  Dr.  W.  H.  Framp- 
ton,  Dr.  Edward  Rutledge,  Dr.  J.  C.  Mitchell,  Dr.  E.  L.  Jager,  Dr. 
F.  B.  Johnson,  Dr.  C.  F.  Bullock. 


46  AIE  SERVICE  MEDICAL. 

Chicago,  III. — Illinois  Charitable  Eye  and  Ear  Infirmary. 

Officers  iu  charge,  Maj.  Casey  A.  Wood,  M.  R.  C. ;  Maj.  Nerval  H.  Pierce, 
M.  R.  C. ;  Capt.  Francis  Laue,  M.  R.  C. ;  Lieut.  Eugeue  Cary,  M.  R.  C. ; 
Lieut.  Charles  P.  Small,  M.  R.  C. 
Examining  board :  President,  Capt.  Charles  E.  Morrison.  S.  C. ;  Lieut.  For- 
rest H.  Sholts,  S.  C. ;  Capt.  George  W.  Woodnick,  M.  R.  C. 
Eye:  Dr.  E.  W.  Reagan. 

Ear,  nose  and  throat:  Dr.  Austin  A.  Hayden,  Dr.  E.  E.  Birmingham. 
Dr.  F.  H.  Henderson,  Dr.  Alfred  Lewy.  Dr.  E.  La  Mothe,  Dr.  F.  S. 
Wilson,  Dr.  R.  J.  Atwood,  Dr.  W.  K.  Spiece. 
General  physical :  Dr.  Frank  Leslie,  Dr.  H.  Smith. 
Volunteer  clerks:   Miss   Helen  Adams,   Miss  Margaret  Monroe,   Miss 
Judith  Cattell. 
Chillicothe,  Ohio. — Base  Hospital,  Camp  Sherman. 

Officer  in  charge,  Maj.  C.  R.  Holmes,  M.  R.  C. ;  Maj.  Casey  Wood,  M.  R.  C, ; 

Capt.  S.  Rinehart,  M.  R.  C. ;  Lieut.  W.  L.  Freyhof,  M.  R.  C.  ^ 
Examining  board:  President,  Division  Signal  Officer;  First  Lieut.  Brose 
S.  Home,  M.  R.  C. 
Cincinnati,  Ohio. — Cincinnati  General  Hospital. 

Officer  in  charge,  Capt.  Arthur  C.  Bachmeyer,  M.  R.  C. 
Examning  board :  President,  Capt.  Dudley  B.  Lavprence,  S.  C. ;  Capt.  Arthur 
C.  Bachmeyer,  M.  R.  C. 
Eye:   Dr.  Victor  Ray.   Dr.  Fred  Lamb,  Dr.   Jesse  Wyler.  Dr.   Wylie 
Ayres,  Dr.  Clarence  King,  Dr.  John  Ranley,  Dr.  Walter  Forchheimer. 
Ear,  nose,  and  throat :  Dr.  Samuel  Iglauer,  Dr.  Horace  Tangeman,  Dr. 
Walter  E.  Murphy,  Dr.  Robert  Stevenson,  Dr.  William  Mithoefer, 
Dr.  William  C.  Harris,  Dr.  Charles  C.  Jones. 
General  physical :   Dr.   Mark  A.   Brown,   Dr.   Oscar  Berghausen,  Dr. 
Arthur  E.  Osmond,  Dr.  William  J.  Graf,  Dr.  Edward  A.  Wagner, 
Dr.  E.  C.  Steinharter. 
Cleveland,  Ohio. — Lakeside  Hospital. 

Officer  in  enlarge,  Capt.  .John  M.  Ingersoll.  M.  R.  C. 

Examining  board :  President,  Capt.  Madison  Bentley,  S.  C.     Capt.  F.  E. 
Cutler,  M.  R.  C. 

Eye:  Dr.  W.  E.  Bruner,  Dr.  W.  C.  Tuckerman,  Dr.  R.  B.  Metz,  Dr. 

S.  H.  Monson.  Dr.  W.  P.  Chamberlin,  Dr.  P.  G.  Moore. 
Ear,  nose  and  throat :  Dr.  C.  E.  Pitkin,  Dr.  E.  W.  Garrett,  Dr.  W.  S. 
Chamberlin,  Dr.  W.  G.  Mussun,  Dr.  W.  J.  Abbott,  Dr.  A.  E.  Fried, 
Dr.  W.  A.  MedUn,  Dr.  F.  W.  Linn. 
General  physical :  Dr.  C.  E.  Hoover.  Dr.  R.  S.  Dinsmore,  Dr.  L.  H. 
Stewart,  Dr.  L.  W.  Ladd,  Dr.  P.  M.  Spurney,  Dr.  C.  T.  Bahler,  Dr. 
E.  H.  Cox,  Dr.  K.  H.  Martzloff,  Dr.  A.  B.  Denison,  Dr.  R.  E.  Mosi- 
man,  Dr.  D.  V.  Rosenberg. 
Columbus,  Ohio. 

Officer  in  charge,  Capt.  Franklin  E.  Cutler,  M.  R.  C. ;  Lieut.  A.  H.  Seeds, 

M.  R.  C. 
Examining  board :  President,  Capt.  C.  C.  Jones,  S.  C. 
Eye :  Drs.  Ivor  G.  Clark,  .T.  B.  Alcorn,  A.  W.  Prout. 
Ear,  nose  and  throat :  Drs.  John  E.  Brown,  A.  C.  Wolfe,  C.  H.  Hoffhine. 

H.  G.  Beatty. 
General  physical :  Drs.  J.  W.  Leist,  F.  M.  Stanton.  C.  T.  Okey,  R.  L. 

Barnes,  J.  H.  J.  Upham,  H.  R.  Burbacher,  W.  H.  Hodges. 
Volunteer  clerk:    John  E.  Brown,  jr. 


AIE  SERVICE  MEDICAL.  47 

Coi.UMBTA,  S.  C. — Base  Hospital,  Camp  Jackson. 

Officer  in  charge,  Capt.  Burton  Chance,  M.  R.  C. ;  Capt.  J.  W.  McConnell. 
M.  R.  C. ;  Lieut.  Bertou  Lattin,  M.  R.  C. ;  Lieut.  Wilson  Pendleton,  M.  R.  C. 
Examining    board :    President,    Division    Signal    Officer ;    Lieut.    Bernard 
Barrow,  M.  R.  C. 
Deming,  N.  Mex. — Base  Hospital,  Camp  Cody. 

Officer  in  charge,  Capt.  H,  R.  Carter,  M.  R.  C. ;  Capt.  L.  C.  Covington; 

Lieut.  Ernest  A.  Duncan,  M.  R.  C. ;  Lieut.  E.  E.  Johnson,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Samuel  Roth, 
M.  R.  C. 
Denver,  Colo. — Jf06  Metropolitan  Btiilding. 

Officer  in  charge,  Capt.  Robert  Levey,  M.  R.  C. 

Examining  board :  President,  Capt.  Alfred  W.  Tozzer,  S.  C.     Capt.  Robert 
Levey,  M.  R.  C. 

Eye :  Dr.  Edward  Jackson,  Dr.  D.  G.  •Mouaghau,  Dr.  D.  H.  Coover,  Dr. 

J.  A.  McCaw,  Dr.  H.  H.  Stilwill,  Dr.  William  H.  Crisp. 
Ear,  nose  and  throat :  Dr.  C.  E.  Cooper,  Dr.  Harry  Baura,  Dr.  E.  W. 

Collins. 
General  physical:  Dr.  C.  B.  Van  Zant,  Dr.  Stanley  B.  Eichberg,  Dr. 
E.  H.  Mugrage,  Dr.  Philip  Hillkowitz,  Dr.  George  A.  Moleen. 
Des  Moines,  Iowa. — Ba^e  Hospital,  Camp  Dodge. 

Officer  in  charge,  Maj.  C.  F.  Todd,  M.  R.  C. ;  Capt.  John.  H.  Peck,  M.  R.  C. ; 
Lieut.  Frank  D.  Lusk,  M.  R.  C. ;  Lieut.  L.  Shields,  M.  R.  C. 
"  Examining  board :    President,   Division   Signal   Officer ;   Lieut.   Ralph   W. 
Faus,  M.  R.  C. 
Deteoit,  Mich. — Harper  Hospital. 

Officer  in  charge,  Capt.  George  E.  Frothingham,  M.  R.  C. 
Examining  board:    President,   Capt.    Paul   Magoffin,    S.    C.     Capt.    G.   E. 
Frothingham,  M.  R.  C. ;  Lieut.  Frank  L.  Ryerson,  M.  R.  C. 

Eye:  Dr.  F.  B.  D.  Waltz,  Dr.  D.  L.  Sherwood,  Dr.  Elbert  A.  Martin, 

Dr.  Homer  I.  Kedney. 
Ear,  nose  and  throat:  Dr.  William  A.  Defnet,  Dr.  Howard  W.  Peirce, 

Dr.  Jacob  §.  W>ndel,  Dr.  H.  L.  Simpson. 
General  physical:  Dr.  W.  S.  Gonne,  Dr.  E.  S.  Crump,  Dr.  Langdon  T. 
Crane,  Dr.  F.  J.  McDonald,  Dr.  Byron  Lowney,  Dr.  Hugo  Freund, 
Dr.  C.  S.  Chase,  Dr.  Max  Ballin,  Dr.  Plinn  F.  Morse. 
Volunteer  clerks:  Miss  Marjorie  McCallum,  Miss  Sarah  Miller,  Miss 
Lena  Murray,  Miss  Mary  E.  Grover. 
FoKT  Sam  Houston,  Tex. — Base  Hospital,  Camp  Travis. 

Officer  in  charge,  Maj.  P.  J.  H.  Farrell,  M.  R.  C. ;  Capt.  James  H.  Agnes. 
M.  R.  C. ;  Capt.  Theodore  Dorset,  M.  R.  C. ;  Lieut.  Herman  H.  Bassler, 
M.  R.  C. 
Examining  board :  President,  Di\4sion  Signal  Officer ;  Lieut.  Arthur  F.  Mc- 
Donald, M.  R.  C. 
Fort  Sill,  Okla. — Base  Hospital.  Camp  Doniphan. 

Officer  in  charge,  Capt.  A.  C.  Magruder,  M.  R.  C. ;  Lieut.  J.  H.  Anderson. 

M.  R.  C. ;  Lieut.  R.  Hudston,  M.  R.  C. ;  Lieut.  L.  H.  Nahum,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  David  R.  Scott, 
M.  R.  C. 
Fort  Riley,  Kans. — Base  Hospital,  Camp  Funston. 

Officer  in  charge,  Maj.  P.  D.  McNaughton,  M.  R.  C. ;  Capt.  Richard  Bow, 
M.  R.  C. ;  Capt.  K.  E.  Williams,  M.  R.  C. ;  Lieut.  David  R.  Scott,  M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer;  Lieut.  Edward  J. 
Howland,  M.  R,  C. 
89118—19 4 


48  AIE  SERVICE  MEDICAL. 

I'OET  WoBTH,  Tex. — Base  Hospital,  Camp  Botoie. 

Officer  in  charge,   Capt.  J.  H.   Dillon,   M.  R,   C. ;   Capt.   W.   J.  Mathers, 
M.  R.  C. ;  Lieut.  Alex.   .Tosewich,  M.  R.   C. ;  Lieut.  O.  F.   Rogers,  jr., 
M.  R.  C. 
Examining  board:   President,   Division   Signal   Officer;   Lieut.  Harper  L. 
Proctor,  M.  R.  C. 
Gaeden  City,  L.  I. — Base  Eosiptal,  Camp  Mills. 

Officer  in  charge,  Capt.  E.  F.  Krug,  M.  R.  C. ;  Lieut.  Edward  F.  Sampson, 

M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer;  Lieut.  Vctor  E.  Bel- 
linger, M.  R.  C. 
Greenville,  S.  C. — Base  Hospital,  Camp  Sevier. 

Officer  in  charge,  Maj.  G.  M.  Coates,  M.  R.  C. ;  Capt.  H.  D.  Pierce,  M.  R.  C. ; 

Lieut.  Geo.  McLean,  M.  R.  C. ;  Lieut.  T.  G.  Schnabel,  M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer;   Lieut.  Arthur  W. 
Carley,  M.  R.  C. 
Hattiesburg,  Miss. — Base  Hospital,  Camp  Shelby. 

Officer  in  charge,  Capt.  O.  L.  Smith,  M.  R.  C. ;  Lieut.  Malcolm  R.  Brewer, 

M.  R.  C. ;  Lieut.  Chas.  S.  Kibler,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Maurice  Wil- 
liamson, M.  R.  C. 
Houston,  Tex. — Base  Hospital,  Camp  Logan. 

Officer  in  charge,  Capt.  F.  F.  Howard,  M.   R.   C. ;   Li^ut.  J.  H.   Brown, 
M.  R.  C. ;  Lieut.  Frank  E.  Mera,  M.  R  C ;  Lieut  D.  F.  O'Connor,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  Geo.  R.  Beebe, 
M.  R.  C. 
Indianapolis,  Ind. — Indiana  University  School  of  Medicine. 
Officer  in  charge,  Capt.  Ernest  Dew.  W.  Wales,  M.  R.  C. 
Examining  board :  President,  Capt.  J.   S.  Reeves,   S.  C. ;  Lieut.  Bernard 
J.  Larkin,  M.  R.  C. 

Dr.  J.  F.  Barnhill,  Dr.  J.  M.  Cunningham,  Dr.  J.  D.  Garrett,  Dr.  S.  A. 
Johnson,  Dr.  J.  A.  MacDonald,  Dr.  F.  A.  Morrison,  Dr.  W.  N.  Sharp, 
Dr.  J.  D.  Whitaker,  Dr.  M.  J.  Barry,  Dr.  T,  W.  De  Hass.  Dr.  M.  N. 
Hadley,  Dr.  A.  C.  Kimberlin,  Dr.  A.  L.  Marshall,  Dr.  J.  R.  Newcomb, 
Dr.  C.  R.  Strickland,  Dr.  J.  W.  Wright,  Dr.  G.  S.  Bond,  Dr.  T.  J. 
Dugan,  Dr.  T.  C.  Hood,  Dr.  E.  S.  Knox,  Dr.  C.  H.  McCaskey,  Dr.  F. 
V.  Overman,  Dr.  A.  L.  Thurston,  Dr  J.  K.  Worthington,  Dr.  J.  W. 
Carmack,  Dr.  W.  H.  Foreman,  Dr.  W.  F.  Hughes,  Dr.  D.  W.  Layman, 
Dr.  J.  Don  Miller,  Dr.  R.  E.  Repass,  Dr.  W.  S.  Tomlin. 
Volunteer  clerks:  Miss  May  Hubbard  Joss,  Miss  Genevive  Scoville, 
Mrs.  M,  J.  Barry,  M,  D.,  Miss  Stillson,  Miss  Frances  Morrison, 
Miss  Ruth  Taggart. 
Ithaca,  N.  Y. — Cornell  University. 

Officer  in  charge,  Capt.  Samuel  A.  Munford,  M.  R.  C. 

Examining  board :  President,  Capt.  Wm.  P.  Field,  S.  C. ;  Lieut.  Edward  R. 
Sibley,  M.  R.  C. 
Eye,   ear,   nose,    and   throat:    Dr.   L.   Coville,   Dr.    J.    S.    Kirkendall, 
Dr.  R.  C.  Willson. 
Kansas  City,  Mo. — Christian  Church  Hospital. 

Officer  in  charge,   Capt.  Francis  M.   McCallum,   M.   R.   C. ;   Lieut.   E.   S. 

Ingersoll,  M.  R.  C. 
Examining  board:  President,  Capt.  H.  C.  Allen,   S.  C. ;  Lieut.  Theo.   S. 
Blakesley,  M.  R.  C. ;  Lieut.  Clinton  K.  Smith,  M.  R.  C. 

Eye :  Dr.  A.  W.  McAlester,  Dr.  H.  R.  Look,  Dr.  Frank  L.  Sanders. 


AIR  SERVICE  MEDICAL.  49 

Kansas  City,  Mo. — Christian  Church  Hospital — Continued. 
Examining  board — Continued. 

Ear,  nose  and  throat :  Dr.  John  L.  Myers. 

General  physical :  Dr.  Miller  W.  Rice,  Dr.  Frank  J.  luen.  Dr.  William 
R.  James,  Dr.  Jabez  N.  Jackson,  Dr.  Franklin  Murphy,  Capt.  Calvin 
L.  Cooper,  Dr.  F.  M.  McCallum,  Lieut.  George  Cooper. 
Volunteer  clerks:  Mrs.  May  B.  McClary*   Private  Homer  Lyle,  Ralph 
P.  Melendy,  Mr.  E.  J,  Sweeney,  Mr.  G.  M.  Babst. 
Linda  Vista,  Cal. — Base  Hospital,  Camp  Kearney. 

OflBcer  in  charge,  Capt.  R.  L.  Anthony,  M.  R,  C. ;  Capt.  Don  Jacobs,  M.  R. 

C. ;  Lieut.  H.  K.  Berkley,  M.  R.  C. ;  Lieut.  Ernest  H.  Falconer,  M.  R.  C. 
Examining  board  :  President,  Division  Signal  Officer ;  Lieut.  Guy  E.  Stewart, 
M.  R.  C. 
Little  Rock,  Akk. — Base  Hospital,  Camp  Pike. 

Officer  in  charge,  Capt.  Vinsonhalor,  M.  R.  C. ;  Capt.  Edward  E.  Evans, 
M.  R.  C. ;  Lieut.  A.  G.  Compton,  M.  R.  C. ;  Lieut.  C,  R.  Comstock,  M.  R.  C. 
Examining   board:    President,    Division    Signal    Officer;    Lieut.    Paul    B. 
Clayton,  M.  R.  C. 
Los  Angeles,  Cal. — University  of  California. 

Officer  in  charge,  Capt.  William  H.  Roberts,  M.  R.  C. 

Examining  board :  President,  Capt.  George  Nichols,  S.  C. ;  Capt.  William  H. 
Roberts,  M.  R.  C. 
Eye:   Dr.  W.  H.  Dudley,  Dr.  A.  L.  Kelsey,  Dr.  L.  W.  Mansur,  Dr. 

F.  D.  Bullard,  Dr.  R.  W.  Graham. 

Ear,   nose  and   throat:   Dr.   Hill   Hastings,   Dr.   C.   R.   K.    Swetnam, 
Dr.  C.  H.  Montgomery,  Dr.  F.  J.  Old,  Dr.  J.  M.  Brown,  Dr.  Charles 

G.  Stivers. 

General  physical :  Dr.  Bertnard  Smith,  Dr.  H.  H.  Lissner,  Dr.  A.  B. 
Perky,  Dr.  R.  L.  Cunningham,  Dr.  C.  H.  Peppers,  Dr.  C.  E.  Carter, 
Dr.  C.  W.  Bonynge,  Dr.  George  Piness. 
Louisville,  Ky. — Base  Hospital,  Camp  Taylor. 

Officer  in  charge,  Maj.  F.  Monge,  M,  R.  C. ;  Maj.  W.  H.  Wilder,  M.  R.  C. ; 

Capt.  M.  J.  Lichty,  M.  R.  C. ;  Lieut.  Willard  D.  Mayer,  M.  R.  C. 
Examining  board :  President,  Di\ision  Signal  Officer ;  Lieut.  Clarence  H. 
Ketterer. 
Macon,  Ga. — Base  Hospital,  Camp  Wheeler. 

Officer  n   charge,   Capt.    Solon   Cameron,   M.   R.    C. ;    Capt.   A.    M.   Jacob, 

M.  R.  C. ;  Capt.  Ernest  Rau,  M.  R.  C. ;  Lieut.  M.  J.  Radin,  M.  R.  C. 
Examining  board :  President,  Division  Signal  Officer ;  Lieut.  James  B.  Car- 
roll, M.  R.  C. 
Memphis,  Tenn. — Exchange  Building. 

Officer  in  charge,  Maj.  E.  C.  Ellett,  M.  R.  C. ;  Lieut.  John  J.  Shea,  M.  R.  C. 
Examining  board:  President.  Capt.  Thomas  Walkup,  S.  C.      Lieut.  James 
B.  Stanford,  M.  R.  C. 

Eye :  Dr.  Robert  Fagin,  Dr.  J.  F.  Minor,  Dr.  Harry  Minor. 

Ear,  nose,  and  throat:  Dr.  W,  L.  Simpson,  Dr.  Fontaine  Moore,  Dr. 

J,  B.  Blue,  Dr.  A.  C.  Lewis. 
General  physical :  Dr.  George  Williamson,  Dr.  Percy  Wood,  Dr.  Greorge 
Cartley,  Dr.  L.  W.  Haskell. 
Minneapolis,  Minn. — University  of  Minnesota. 

Officer  in  charge,  Lieut.  Aloysius  S.  Fleming,  M.  R.  C;  Capt.  F.  O.  Todd, 

M.  R.  C. 
Examining  board:  President,  Capt.  C.  C.  Jones,  S.  C.     Lieut.  Charles  E. 
Connor,  M.  R.  C. 


50  AIR  SERVICE  MEDICAL. 

Minneapolis,  Minn. — University  of  Minnesota — Continued. 
Examining  board — Continued. 

Eye :  Dr.  W.  W.  Lewis,  Dr.  J.  S.  Reynolds,  Dr.  C.  W.  Fogarty,  Dr.  G.  B. 
Strout,  Dr.  John  C.  Brown,  Dr.  E.  A.  Loomis,  Dr.  E.  R.  Bray.  Dr. 
Howard  S.  Clark,  Dr.  J.  S.  Macnie,  Dr.  Frank  E.  Burcb. 
Ear,  nose  and  throat :  Dr.  F.  .J.  Pratt,  Dr.  W.  E.  Patterson,  Dr.  J.  D. 
Lewis.  Dr.  J.  A.  Pratt,  Dr.  C.  C.  Cowin,  Dr.  J.  A.  Watson,  Dr.  H.  J. 
Welles,  Dr.  F.  N.  Knap,  Dr.  W.  E.  Camp,  Dr.  H.  E.  Binger,  Dr. 
WilUam  R.  Murray,  Dr.  J.  T.  Litchfield. 
General  physical :  Dr.  George  D.  Head,  Dr.  James  W.  George,  Dr.  J.  M. 
Lajoie.  Dr.  J.  G.  Cross,  Dr.  W.  H.  Aurand,  Dr.  J.  Fowler  Avery, 
Dr.  E.  L.  Baker,  Dr.  Jalmar  H.  Simons,  Dr.  S.  H.  Baxter,  Dr.  A.  E. 
Benjamin,  Dr.  E.  L.  Gardner,  Dr.  R.  A.  Johnson,  Dr.  Ralph  Morris, 
Dr.  Walter  J.  Marcley. 
Volunteer  clerks:  Miss  Marion  A.  Tebbets.  Miss  Helen  Forrest,  Miss 
Clare  Lougee,  Miss  Sydney  Pattee,  Miss  Elizabeth  Anderson,  Miss 
Marie  Lobdell,  Miss  Helen  Scanlon,  Miss  Gladys  Pattee,  Miss  Mar- 
guerite Owen,  Miss  Grace  Richter,  Miss  Henrietta  Pringle. 
Montgomery,  Ala. — Base  Hospital,  Camp  Sheridan. 

Officer  in  charge,  Maj.  Ross  H.  Skillern,  M.  R.  C. ;  Capt  H.  W.  Hoagland, 

M.  R.  C. ;  Capt.  Allen  Hamilton,  M.  R.  C. ;  Capt.  G.  W.  Jean,  retired. 
Examining  board:   President,  Division   Signal  Officer;   Lieut.  Bi'ickhouse 
Wilson,  M.  R.  C. 
New  Haven,  Conn. — Medical  Department,  Tale  University. 
Officer  in  charge,  Capt.  Harold  S.  Arnold,  M.  R,  C. 

Examining  board:   President,  Capt.  Harold  S.  Arnold,  M.  R.  C.     Lieut. 
James  A.  Honeij,  M.  R.  C. 

Eye:  Dr.  Samuel  M.  Hammond. 

Ear,  nose  and  throat:  Dr.  Henry  M.  Swain,  Dr.  Frederick  N.  Sperry. 

Dr.  Frank  L.  Phillips. 
General  physical:  Dr.  Wilder  Tileston,  Dr.   Isao  Hirata,  Dr.   Israel 

Kleiner,  Dr.  Edgar  N.  Johnson. 
Volunteer  clerks:   Mrs.  Eugene  Blake,   Mrs.  John  W.   Stevens,   Mrs. 
Harold  S.  Arnold. 
(Part  of  equipment  given  by  Mrs.  Harris  Whittemore,  Naugatuck,  Conn.) 
New  Orleans,  La. — Eye,  ear,  nose,  and  throat  hospital. 
Officer  in  charge,  C.  S.  Robert  C.  Lynch,  U.  S.  A. 

Examining  board:  President,  Capt.  Albert  Kramer,  S.  C.     C.  S.  Edmund 
Moss,  U.  S.  A. 

Eye:  Dr.  Henry  Dickson  Bruns,  Dr.  Ernest  A.  Robin. 
Ear,  nose,  and  throat:  Dr.  George  J.  Taquine. 
General  physical :  Dr.  Charles  L.  Eshleman. 
Volunteer  clerk:  Mrs.  M.  E.  Cline. 
New  Tokk  City,  N.  Y. — Manhattan  Eye  and  Ear  Hospital. 

Officer  in  charge,  Capt.  Morgan  Grace,  S.  C. ;  Lieut.  J.  D.  Richards ;  Lieut. 

R.  H.  Fowler. 
Examining  board:  President,  Capt.  Morgan  Grace,  S.  C.     Lieut.  Roderick 
A.  Jones,  S.  C. ;  Capt.  David  H.  Webster,  M.  R.  C. ;  Lieut.  Grover  C. 
Otrich,  M.  R.  C. 

Eye :  Dr.  James  Wilson  Cassell,  Dr.  Edgar  S.  Thomson,  Dr.  Malcolm  C. 
Rose,  Dr.  Frank  Van  Fleet,  Dr.  Charles  W.  Kinney,  Dr.  Martin 
Cohen,  Dr.  Herbert  W.  Wootton,  Dr.  John  Ronalds  Shannon,  Dr. 
Henry  R.  Skeel,  Dr.  Erasmus  A.  Pond,  Dr.  Isaac  Hartshorne,  Dr. 
Wm.  H.  Holzapfel,  Dr.  Alfred  D.  Mittendorf,  Dr.  Lewis  Webb  Crig- 


AIE  SERVICE  MEDICAL.  51 

New  York  City,  N.  Y. — Manhattan  Eye  and  Ear  Hospital — Continued. 
Examining  board — Continued. 
Eye — Continued, 
ler,  Dr.  David  H.  Jones,  Dr.  Frank  Cliurcliill,  Dr.  Julius  I.  Klepper, 
Dr.  James  F.  Smitti,  Dr.  T.  Francis  Bridgman. 
Ear,  nose  and  tliroat:  Dr.  Hampton  P.  Howell,  Dr.  Phillip  D.  Ker- 
rison,  Dr.  Edgar  H.  F'arr,  Dr.  Warren  C.  McFarland,  Dr.  W.  L. 
Culbert,  Dr.  Frank  H.  Bartlett,  Dr.  ,John  R.  Page,  Dr.  Walter  F. 
Babb,  Dr.  John  E.  Welsh,  Dr.  John  D.  Richards,  Dr.  Stephen  W. 
Roof,  Dr.  James  J.  King,  Dr.  Louis  Hubert,  Dr.  George  E.   Steel, 
Dr.  John  B.  Rae. 
General  physical:  Dr.  Herbert  S.  Carter,  Dr.  Heman  L.  Dowd,  Dr. 
Charles  E.  Weber,  Dr.  T.  Stuart  Hart,  Dr.  B.  Wallace  Hamilton, 
Dr.    William   B.    Boyd,    Dr.    Walter    P.    Anderton,    Dr.    Joseph    C. 
Stammers.  % 

Volunteer  clerks:  Mrs.  J.  W.  Ryder,  Miss  Iris  Wilder. 
Omaha,  Nebr. — Vniversity  of  Nebraska,  Medical  Department. 

Officer  in  charge,  Capt.  Adolph  B.  Linquest,  M.  R.  C. ;  Capt.  E.  R.  Lewis, 

M.  R.  C. ;  Lieut.  Claude  Thomas  Uren,  M.  R.  C. 
Examining  board:  President,  Lieut.  Charles  J.  Glidden,  S.  C.     Lieut.  Roy 
Crook,  M.  R.  C. 

Eye:  Dr.  Louis  B.  Bushman,  Dr.  Sanford  Giffiord,  Dr.  James  M.  Pat- 
ton,  Dr.  Wm.  P.  Wherry, 
Ear,   nose   and  throat:    Dr.   Harry  L.   Arnold,   Dr.   Chas.    S.   James, 
Dr.  William  F.  Callfas,  Dr.  A.  Ray  Knode,  Dr.  Clarence  Rubendahl, 
Dr.  W.  P.  Haney,  Dr.  John  B.  Potts. 
General   physical:   Dr.   Rodney   W.   Bliss,   Dr.   LeRoy   Crummer,   Dr. 
Adolph  Sachs,  Dr.  Edson  L.  Bridges,  Dr.  Arthur  J.  Dunn,  Dr.  C.  C. 
Tomlinson,  Dr.  Frank  M.  Conlin,  Dr.  J.  Clyde  Moore,  Dr.  Warren 
Y.  Thompson. 
Peteksbtjrg,  Va. — Base  Hospital,  Camp  Lee. 

Officer  in  charge,  Maj.  E.  W.  Day,  M.  R.  C. ;  Capt.  John  P.  Faber,  M.  R.  C. ; 

Capt  B.  R.  Kennon,  M.  R.  C. ;  Lieut.  F.  J.  Smith,  M.  R.  C. 
Examining  board :    President,    Division    Signal    Officer ;    Lieut.   Frank   L, 
Field,  M.  R.  C. 
Philadelphia,  Pa. — University  of  Pennsylvania. 

Officer  in  charge,  Lieut.  Isaac  H.  Jones,  M.  R.  C.    Lieut.  H.  Maxwell  Lang- 
don,  M.  R.  C. 
Examining  board  No.  1 :  President,  Capt.  C.  C.  Jones,  S.  C.    Lieut.  Ben  C. 

Gile,  M.  R.  C. 
Examining  board  No.  2 :  President,  Lieut.  Frank  N.  Cordner,  S.  C.    Lieut. 
John  P.  Gallagher,  M.  R.  C. 

Eye:  Dr.  John  A.  Colgan,  Dr.  J.  Scott  Fritch,  Dr.  P.  L.  Balentine. 
Ear,  nose  and  throat:  Dr.  Lewis  Fisher,  Dr.  A.   Spencer  Kaufman, 

Dr.  Fielding  O.  Lewis,  Dr.  Arthur  J.  Wagers. 
General  physical:  Dr.  Geo.  M.  Ferguson,  Dr.  Francis  Ashley  Faught, 
Dr.  J.  V.  C.  Roberts. 
PiTTSBXiBGH,  Pa. — Eye  and  Ear  Hospital. 

Officer  in  charge,  Capt.  Wm.  C.  Meanor,  M.  R.  C. ;  Capt.  E.  W.  Day,  M.  R. 

C. ;  Lieut.  Carl  Henning,  M.  R.  C. 
Examining  board:  President,  Capt.  G.  V.  Hamilton,  S.  C.     Lieut.  Geo.  S. 
Cunningham,  M.  R.  C. 
Eye :  Dr.  C.  W.  Jennings,  Dr.  G.  E.  Curry,  Dr.  S.  L.  Koch. 
Ear,  nose  and  throat :  Dr.  J.  Homer  McCready,  Dr.  Watson  Marshall, 
Dr.  Arthur  Fisher. 


62  AIE  SERVICE  MEDICAL. 

Pittsburgh,  Pa. — Eye  and  Ear  Hospital — Continued. 
Examining  board — Continued. 

General  physical :  Dr.  James  C.  Burt.  Dr.  A.  F.  B.  Morris,  Dr.  J.  M. 
Long,  Dr.  Samuel  R.  Haythorne,  Dr.  P.  M.  Lloyd,  Dr.  I.  J.  Moyer, 
Dr.  James  K.  Evenhart,  Dr.  C.  L.  Palmer,  Dr.  J.  I.  Johnston,  Dr. 
Karl  Emmerling. 
Volunteer  clerks :  Miss  Turpin,  Miss  Virginia  Kopp,  Miss  Dorothy 
Liggitt,  Miss  Helen  Turpin,  Miss  Mary  Painter,  Miss  Agate  Brown, 
Mrs.  James  C.  Burt,  Miss:  Carolyn  Gibbs,  Miss  Laura  Biggert,  Miss 
Alice  Brown. 
Portland,  Me. — Main  Eye  and  Ear  Infirmary. 

Officer  in  charge,  Lieut.  Carl  D.  Gray,  M.  R.  C. 

Examining  board :  President,  Lieut.  Julius  C.  ()ram,*S.  C.     Lieut.  Wm.  W. 
Gill. 

Eye,  ear,  nose,  throat,  and  general  physical :  Dr.  E.  E.  Holt,  jr..  Dr. 
Owen  P.  Smith,  Dr.  Stanwood  E.  Fisher,  Dr.  John  Allen,  Dr.  Phillip 

E.  Tuliey,  Dr.  John  W.  Bowers,  Dr.  George  L.  Christy,  Dr.  Oilman 
Davis,  Dr.  Fred  L.  Chenery. 

Volunteer  clerks :  Miss  Bertha  Rogers,  Miss  Miriam  Moulton. 
Portland,  Oreg. — 

Officer  in  charge,  Capt.  Joseph  L.  McCool,  M.  R.  C. 

Examining  board :  President,  Lieut.  Frauk  N.  Cordner,  S.  C. 

Eye:  Dr.  Harry  M.  Hendershott,  Dr.   Frederick  A.  Kiehle,  Dr.   Wm.   L. 

Wood,  Dr.  Guy  H.  Ostrander. 
Bar,  nose  and  throat :  Dr.  Frank  Kistner,  Dr.  Wilson  Johnston,  Dr.  Ralph 

F.  Davis,  Dr.  Robert  B.  Karkeet. 
General  physical :  Dr.  Murray  M.  Levy,  Dr.  C.  Stuart  Menzies,  Dr.  I.  C 

Brill,  Dr.  T.  Homer  Coffen,  Dr.  C.  F,  Bloom. 
Volunteer  Clerks:  Miss  Margaret  Russell,  Miss  Edna  Christia,  Miss  Mollie 
Flood. 
Richmond,  Va. — Memorial  Hospital. 

Officer  in  charge,  Lieut.  William  W.  Gill,  M.  R.  C. 

Examining  board :  President,  Capt.  A.  G.  C.  Sage,  S.  C.    Lieut.  William  W. 
Gill,  M.  R.  C. 

Eye,  ear,  nose  and  throat:  Dr.  Joseph  A.  White.  Dr.  W.  L.  Mason, 
Dr.  John  Dunn,  Dr.  Karl  Blackwell,  Dr.  Clifton  Miller,  Dr.  D.  A, 
Kuyk,  Dr.  W.  B.  Hopkins. 
General  physical :  Dr.  Manfred  Call,  Dr.  M.  P.  Rucker,  Dr.  M.  O. 
Burke,  Dr.  Douglas  Vanderhoof,  Dr.  H.  W.  Randolph,  Dr.  T.  N. 
Barnett,  Dr.  J.  M.  Hucheson,  Dr.  E.  B.  Talbot,  Dr.  Herbei't  Mann, 
Dr.  F.  P.  Righter,  Dr.  W.  S.  Bordon,  Dr.  Robt.  S.  Bosher,  Dr.  Wil- 
liam H.  Higgins. 
RocKFORD,  III. — Base  Hospital,  Camp  Grant. 

Officer  in  charge,  Maj.  N,  H.  Pierce,  M.  R.  C. ;  Maj.  T.  A.  Woodruff,  M.  R. 
C. ;  Capt.  John  H.  McClellan,  M.  R.  C. ;  Lieut.  H.  E.  B.  Pardee,  M.  R.  C. 
Examining   board :    President,   Division    Signal    Officer ;    Lieut.    Edwin   G. 
Schwartz,  M.  R.  C. 
St.  Louis,  Mo. — Washington  University. 

Officer  in  charge.  Capt.  Harry  W.  Lyman.  M.  R.  C. ;  First  Lieut.  Joseph  J. 

Reilly,  M.  R.  C. 
Examining   board:    President,    Capt.    Chas.    H.    Hammond,    S.    C. ;    Capt. 
Frederick  C.  Simon,  M.  R.  C. 

Eye:  Dr.  A.  E.  Ewing,  Dr.  W.  E.  Shahan,  Dr.  John  Green,  jr.,  Dr. 
W.  F,  Hardy,  Dr.  H.  M.  Post,  jr.,  Dr.  M.  Wiener,  Dr.  J.  H.  Gross, 
Dr.  Max  Jacobs,  Dr.  F.  C.  Donnell,  Dr.  Emmett  D.  North,  Dr.  F.  P. 
Parker,  Dr.  J.  F.  Shoemaker,  Dr.  G.  F.  Paine,  Dr.  C.  D.  Scott,  Dr. 

F.  O.  Schwartz. 


AIB  SERVICE  MEDICAL.  53 

St.  Louis,  Mo.— Washinffton  University — Continued. 
Examining  board — Continued. 

Ear,  nose  and  throat:  Dr.  A.  F.  Koetter,  Dr.   S.  B.  Westlake,  Dr.  E.  T. 
Senseny,  Dr.  L.  A,  Kempff,  Dr.  W.  E.  C.  Bryan,  Dr.  G.  B.  Hourn. 
General  physical :   Dr.  George  Dock,   Dr.  R.  K.  Andrews,  Dr.  H.  S. 
O'Connell,  Dr.  H.  C.  Peacock,  Dr.  W.  K.  Brown,  Dr.  W.  H.  Omsted, 
Dr.  Ellsworth  Smith,  Dr.  S.  Moore,  Dr.  F.  H.  Eberhard,  Dr.  C.  S. 
Gilliland,  Dr.  A.  R.  Tormey,  Dr.  Frank  N.  Wilson,  Dr.  A.  McClory, 
Dr.  S.  T.  Lipsitz,  Dr.  G.  Canby  Robinson,  Miss  W.  McNitt,  Dr.  L.  H. 
Hempelmann,  Dr.  A.  R.  Schreffler,  Dr.  T.  C.  Lyter,  Dr.  E.  P.  Buddy, 
Dr.  J.  L.  Tierney,  Dr.  Warren  Elmer,  Dr.  Chas.  H.  Neilson,  Dr.  J.  J. 
Singer. 
Volunteer  clerks:   Miss  Anita   Brinkmeyer,   Miss   Edith   Foster.   Mr. 
G.  W.  Tucker. 
Salt  Lake  City,  Utah. — Boston  Building. 

Officer  in  charge,  Oapt.  Louis  Levy,  M.  R.  O. 

Examining  board :  President,  Capt.  Walter  C.  Fisher,  S.  C. ;  Lieut.  Robert 
R.  Hampton,  M.  R.  C. 
Eye:  Dr.  A.  R.  Irvine,  Dr.  L.  W.  Snow,  Dr.  G.  V.  Schramm,  Dr.  E.  L. 

Le  Compte,  Dr.  D.  Lindsay. 
Ear,  nose  and  throat:  Dr.  Fred  Stauffer,  Dr.  A.  J.  Ridges,  Dr.  F.  H. 

Raley. 
General  physical :  Dr.  C,  L.  Shields,  Dr.  J.  C.  Landenberger,  Dr.  W.  R. 
Tyndale,  Dr.  H.  B.  Felts,  Dr.  H.  P.  Kirtley,  Dr.  W.  T.  Ward,  Dr. 
Ray  Groesbeck. 
San  Antonio,  Tex. — Robert  B.  Green  Memorial  Hospital. 

Officer  in  charge,  Capt.  Robert  J.  Hunter,  M.  R.  C. ;  Lieut.  Douglas  Ed- 
wards, M.  R.  C. 
Examining  board:  President,  Capt.  Rufus  Scott,  jr.,  S.  C. ;  Lieut.  Russell 
MacDonald,  S.  C. ;  Lieut.  Edward  B.  Collins,  M.  R.  C. ;  Lieut.  Wilson  M. 
Basset,  M.  R.  C. 
Eye:  Dr.  Applewhite. 

Ear,  nose  and  throat :  Dr.  Moss,  Dr.  Sykes. 
General  physical:  Dr.  Hicks. 
Volunteer  clerk :  Miss  Lathrop. 
San  Francisco,  Cax. — University  of  California  Medical  Department. 

Officer   in   charge,   Capt.    Henry   W.    Horn,    M.   R.    C. ;    Lieut.    Frederick 

Lewitt,  M.  R.  C. 
Examining  board :  President,  Capt.  George  M.  Stratton,  S.  C. ;  Capt.  El- 
bridge  J.  Best,  M.  R.  O. 
Eye:  Dr.  Walter  S.  Franklin,  Dr.  Edmund  Glaser. 
General  physical :  Dr.  Franklin  Cookingham. 
Seattle,  Wash. — American  Bank  Building. 

Officer  in  charge,  Capt.  Richard  H.  Perry,  M.  R.  0. 

Examining  board :  President,  Capt.  G.  L.  Jones,  S.  C. ;  Lieut.  George  W. 
Beeler,  M.  R.  C. 

Eye,  ear,  nose  and  throat:  Dr.  Conner  B.  Gray,  Dr.  W.  F.  Hoffman, 
Dr.  A.  F.  Mattice,  Dr.  H.  V.  Wurdemann,  Dr.  W.  O.  Bell,  Dr.  Henry 
E.  Chase,  Dr.  Walter  K.  Seeley,  Dr.  Hamilton  Stillson,  Dr.  J.  T, 
Dowling,  Dr.  L.  Klemptner,  Dr.  John  A.  McKinnon. 
General  physical :  Dr.  F.  H.  Houston,  Dr.  C.  A.  Rutherford,  Dr.  W.  T. 
Woolley,  Dr.  C.  F.  Davidson,  Dr.  D.  A.  Dowling,  Dr.  N.  A.  Johanson, 
Dr.  H.  J.  Davidson,  Dr.  O.  F.  Lamson,  Dr.  Welden  E.  Young,  Dr. 
E.  G.  Newlauds,  Dr.  Albert  Raymond,  Dr.  James  Shannon,  Dr. 
Montgomery  Russell,  Dr.  O.  J.  West. 


54  AIE  SERVICE   MEDICAL. 

Spartanbubg,  S.  C. — Base  Hospital,  Cam])  Wadsioorth. 

Officer  in  charge,  Ma.i.  W.  P.  BarndoUar,  M.  R.  C. ;   Lieut.  C.  W.  Stiles, 

M.  R.  C. ;  Lieut.  Arthur  F.  Peterson,  M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer;  Capt.  Nathan  S.  D. 
Davis,  3d,  M.  R.  C. 
Sybacuse,  N.  T. — SSI  University  Block. 

Officer  in  charge,  Lieut.  Fedor  L.  Senger,  M.  R.  C. 

Examining    board :    President,    Capt.    V.    A.    C.    Heumon,    S.    C. ;    Lieut. 
Fedor  L.  Senger,  M.  R.  C. 

Eye:  Dr.  Frank  W.  Marlovv,  Dr.  Julius  H.  Kevand,  Dr.  Norman  W. 
Foster,  Dr.  Herbert  L.  Stebbins,  Dr.  G.  Griffin  Lewis,  Dr.  David  F. 
Gillette. 
Eye,  nose  and  throat :  Dr.  Tliomas  H.  Halstead,  Dr.  Harold  G.  Kline, 
Dr.  Samuel  R.  Fowler,  Dr.  George  H.  Rockwell,  Dr.  Mortimer  G. 
Brown,  Dr.  Sargent  F,  Snow,  Dr.  H.  Leland  Fifield. 
General   physical :  Dr.    I.    Harris    Levy,    Dr.    Charles    D.    Post,    Dr. 
Joseph   R.    Wiseman,    Dr.   A.    B.   Larkin,   Dr.    James   Sheehan,   Dr. 
Herbert  C.  Yeckel,  Dr.  Earl  V.  Sweet,  Dr.  Arthur  D.  Meyers. 
ToKONTo,  Caistada. — Tovonto  University,  United  States  Headquarters. 
Officer  in  charge.  Contract  Surgeon  Fred  J.  O'Connor,  U.  S.  A. 
Waco,  Tex. — Base  Hospital,  Camp  McArtJtur. 

Officer  in  charge,  Capt.  N.  H.  Bowman,  M.  R.  C. ;  Capt.  Seaton  Norman, 
M.  R.  C. ;  Capt.  A.  Vander  Veer,  jr.,  M.  R.  C. ;  Lieut.  John  Potts,  M.  R.  C. 
Examining    board :    President,    Division    Signal    Officer ;    Lieut.    Leonard 
Champion,  M.  R.  C. 
Washington,  D.  C. — Episcopal  Eye  and  Ear  Hospital. 

Officer  in  charge,  Capt.  Wm.  F.  Patten,  M.  R.  C. ;  First  Lieut.  S.  A.  Alex- 
ander, M.  R.  C. 
Examining  board :  President,  Col.  Geo.  H.  Crabtree,  U.  S.  A.,  rot. ;  Lieut. 
Col.  Nelson  Gapen,  M.  C. ;  Capt.  R.  M.  JVewport,  S.  C. ;  Capt.  F.  H.  Town- 
send,  S.  C;  Capt.  Robt.  Wrenn,  S.  C;  Lieut.  Waldo  C.  Johnston,  S.  C. ; 
Lieut,  Charles  W.  Hyde,  M.  R.  C. 

Eye:  Dr.  H.  A.  Polkinhorn,  Dr.  V.  B.  Rench,  Dr.  L.  S.  Greene,  Dr. 

R.  S.  Lamb,  Dr.  W.  H.  Fox,  Dr.  A.  H.  Kimball,  Dr.  E.  L.  Morrison. 
Ear,  nose  and  throat:  Dr.  O.  A.  M.  McKimmie,  Dr.  G.  S.  Saffold,  Dr. 
R.  R.  Walker,  Dr.  W.  T.  Parsons,  Dr.  W.  C.  Sparks,  Dr.  E.  A.  Taylor, 
Dr.  D.  B.  Moffett,  Dr.  C.  L.  Billard. 
General  physical :  Dr.  A.  W.  Boswell,  Dr.  J.  L.  Thompson,  Dr.  M.  F. 
Cuthbert,  Dr.  J.  B.  Nichols,  Dr.  Frank  Leech,  Dr.  P.  S.  Roy,  Dr.  E.  T. 
Davidson,  Dr.  W.  I.  Mallory,  Dr  T.  Miller,  jr.,  Dr.  D.  G.  Lewis. 
Volunteer  clerks:  Miss  Eleanor  Martin,  Mrs.  F.  W.  Smith,  Miss  Doro- 
thy Woodworth,   Mrs.   Ward   Brown,   Miss  B.   Gower,   Miss   Stella 
Devine,  Miss  M.  Harrington,  Miss  Alida  Haines,  Miss  E.  C.  Taylor. 
Wrightstown,  N  J. — Base  Hospital,  Camp  Dix. 

Officer  in  charge,  Maj.  Wells  P.  Eagleton,  M.  R.  C. ;  Capt.  Wm.  J.  Hammed, 

M.  R.  C. ;  Capt.  P.  H.  Moore,  M.  R.  C. ;  Lieut.  T.  A.  Smith,  M.  R.  C. 
Examining  board:   President,   Division   Signal   Officer;   Lieut.   Samuel  J. 
Ellison,  M.  R.  C. 
Yaphank,  N.  Y. — Base  Hospital,  Camp  Upton. 

Officer  in  charge,  Maj.  E.  B.  Dench,  M.  R.  C. ;  Capt  T  C.  Richie,  M.  R.  C. ; 

Capt.  Jas.  L.  Wheaton,  M.  R.  C. ;  Lieut.  Edward  J.  Riley,  M.  R.  C. 
Examining  board:  President,  Division  Signal  Officer;  Lieut,  Walter  C. 
Liebmann,  M.  R.  C, 


55b 


CHAPTER  III. 
WORKING  METHODS  OF  PHYSICAL  EXAMINING  UNITS. 


Blank  609  A.  G.  O.  shown  in  figure  1  is  the  only  form  specified  for 
the  examination  of  applicants  for  the  Aviation  Service.  While  this 
blank  is  comprehensive  in  all-important  details,  it  was  not  required 
that  the  examination  should  follow  the  order  of  items.  The  organi- 
zation of  the  work  of  the  unit  was  systematized  with  a  view  to  saving 
time  and  energy  in  the  carrying  out  of  these  examinations.  Such  a 
system  was  especially  necessary  in  a  large  unit  where  from  20  to  75 
men  had  to  be  examined  every  day. 

In  the  actual  working  of  an  Examining  Unit  where  the  number  of 
examiners  is  necessarily  limited,  it  is  convenient  to  map  out  and  sub- 
divide various  types  of  examinations  in  such  a  way  that  the  different 
examiners  comprising  the  unit  may  all  be  busy  at  the  same  time. 
For  purposes  of  description  it  might  be  well  for  the  reader  to  put 
himself  in  the  position  of  an  observer  and  watch  the  method  of 
procedure  with  a  given  group  of  applicants  from  the  moment  they 
enter  this  unit  to  the  time  they  leave.  Various  units  in  different 
parts  of  the  country  have  adopted  proceedings  suitable  to  local  con- 
ditions. If  a  small  number  of  applicants  are  to  be  examined,  the 
following  method  of  procedure  has  been  found  satisfactory : 

The  receiving  sergeant  gives  each  applicant  a  number  as  he  enters 
the  room;  this  number  is  retained  by  him  throughout  the  entire 
examination.  Specimens  of  urine  are  then  secured  and  the  total 
number  of  applicants  for  the  day  is  divided  into  three  groups, 
one  group  being  sent  to  the  eye  examiner,  one  group  for  general 
physical  examination,  and  one  group  for  the  turning-chair  tests,  and 
the  ear,  nose  and  throat  examinations.  In  this  manner  the  ophthal- 
mologist, the  otologist  and  the  internist  are  all  working  simultane- 
ously. It  usually  takes  about  the  same  length  of  time  for  these  three 
types  of  examinations,  so  that  when  the  ophthalmologist  is  finished 
with  his  group,  the  otologist  has  similarly  completed  his  work  and 
is  ready  for  the  next  group.  In  this  manner  these  three  groups 
alternate  so  that  all  of  the  examinations  are  completed  at  about  the 
same  time. 

In  large  cities  where  it  was  necessary  to  examine  from  25  to  50 
applicants,  the  following  so-called  "  Liberty  m.otor  plan  "  was  de- 
vised and  found  very  satisfactory.  (A  quotation  from  Stencil  No.  32 
gives  in  detail  the  workings  of  this  method  of  examining  the 
applicants.) 

For  the  guidance  of  the  various  Physical  Examining  Units  the 
following  standard  "  Liberty   motor "  scheme  of  organization  of 

66 


56  AIB  SEEVIOE  MEDICAL. 

units  was  submitted.  This  was  deduced  from  the  experience  of  a 
large  number  of  units  covering  from  six  to  eight  months'  continuous 
work  and  is  definitely  established  to  be  adequate  to  the  examination 
of  20  applicants  per  day  at  an  average  cost  in  time  to  each  individual 
composing  the  unit  of  not  more  than  55  to  75  minutes  per  day. 

Reference  to  the  schematic  representation  of  this  organization  will 
make  it  plain  that,  beginning  at  7  a.  m.,  for  example,  the  applicants 
appear  before  the  sergeant,  who  takes  the  urine,  strips,  weighs,  meas- 
ures, and  starts  the  records  of  physical  examination ;  at  7.20  the  gen- 
eral phj^sical  examiners  appear  and  find  that  the  sergeant  has,  already 
stripped  and  awaiting  them,  at  least  two  applicants,  one  of  whom 
goes  to  the  examiner  who  is  to  conduct  the  stethoscopic  and  sphygmo- 
manometer examinations,  and  the  other  of  whom  goes  to  the  other 
examiner,  who  is  to  conduct  the  remainder  of  the  general  physical 
examination;  the  two  applicants  then  change  about,  and  upon  com- 
pletion of  the  general  physical  examination  they  dress.  By  that 
time,  7.40,  the  two  ear,  nose  and  throat  specialists  appear  and  at  once 
proceed  to  examine  those  applicants,  as  indicated  in  the  scheme ;  one 
man  conducting  hearing  tests  and  auscultation  of  the  Eustachian 
tubes  only,  the  other  man  with  the  head  mirror  inspecting  drum- 
heads, nares,  pharynx,  and  larynx.  The  applicants  then  change 
about  and  are  completed  as  to  ear,  nose  and  throat  examinations, 
whereupon  they  both  go  to  the  eye  specialists,  who  appear  at  8  a.  m. 
Here  a  change  in  the  order  occurs  in  that  both  applicants  go  to  the 
visual  acuity  and  muscle  balance  tests  at  once,  and  during  the  exami- 
nation of  one  the  second  eye  specialist  conducts  the  color  and  stere- 
oscopic tests  of  the  second  applicant.  The  first  applicant's  visual 
acuity,  muscle  balance,  and  extra-ocular  examination  being  com- 
pleted, he  in  turn  is  subjected  to  the  color  and  stereoscopic  tests,  after 
which  they  are  both  ready  for  mydriatic,  and  as  soon  as  the  mydri- 
asis occurs  their  intra-ocular  examination  is  completed,  and  they  then 
go  to  the  turning-chair  examiner,  who  appears  at  8.20.  As  is  indi- 
cated on  the  diagram,  at  each  stage  of  the  examination  "  culls  " — that 
is,  border-line  cases  or  those  who  will  need  special  follow-up  exami- 
nations— are  set  aside  so  as  not  to  interrupt  the  current  of  regular 
examination  of  the  day's  material,  and  after  completion  of  examina- 
tion of  all  other  applicants  these  "  culls  "  are  then  subjected  to  what- 
ever additional  examination  or  examinations  may  be  considered  nec- 
essary. 

The  "  Liberty  motor  "  scheme  for  conducting  the  work  of  Examin- 
ing Units  has  been  worked  out  with  just  one  object  in  view,  namely, 
to  save  all  possible  time  and  work  for  the  examiners,  arid  at  the  same 
time  to  insure  to  the  service  the  highest  type  of  professional  serv- 
ices in  examining  applicants  for  the  Aviation  Service.  The  usual 
type  of  organization  for  Physical  Examining  Units  includes  two  teams, 
one  working  Mondays,  Wednesdays,  and  Fridays;  the  other  Tues- 
days, Thursdays,  and  Saturdays.    If  the  "  Liberty  motor  "  organiza- 


AIE  SERVIOE  MEDICAL. 


57 


tion  scheme  and  schedule  is  adhered  to,  it  makes  possible  the  careful 
examination  of  as  many  as  20  applicants  per  day  by  the  unit,  at  an 


b- 


ZZ 


O 


< 
X 

_J 
O 

°i 

CD 
CC 

o 

B 


CD 
—I    1^ 

-  21 

-J 


cC 


average  cost  not  greater  than  55  to  75  minutes  per  day,  three  days 
a  week,  to  any  one  member  of  the  unit. 


58 


AIE  SERVICE  MEDICAL. 


Sample    schedule   according    to    "  Liberty    motor "    organization,    two    teams, 

each  working  three  days  per  week. 


O'clock. 

Monday. 

Tuesday. 

Wednesday. 

Thursday. 

Friday. 

Saturday. 

7.00 

Sergeant. 

/Dr.  Jones. 
\Dr.  Allen. 

/Dr.  Smith. 
\Dr.  Bowen. 

/Dr.  Hughes. 
\Dr.  Brown. 

Chair. 

Sergeant. 

Dr.  Nash. 
Dr.  Dodge. 

Dr.  Watts. 
Dr.  Atkins. 

Dr.  Wilson. 
Dr.  Gordon. 

Chair. 

Sergeant. 

Dr.  Jones. 
Dr.  Allen. 

Dr.  Smith. 
Dr.  Bowen. 

Dr.  Hughes. 
Dr.  Brown. 

Chair. 

Sergeant. 

Dr.  Nash. 
Dr.  Dodge. 

Dr.  Watts. 
Dr.  Atldins. 

Dr.  Wilson. 
Dr.  Gordon. 

Chair. 

Sergeant. 

Dr.  Jones. 
Dr.  Allen; 

Dr.  Smith. 
Dr.  Bowen. 

Dr.  Hughes. 
Dr.  Brown. 

Chair. 

Sergeant. 

Dr.  Nash. 
Dr.  Dodge. 

Dr.  Watts. 

7.20,  general  phys- 
ical  

7.40,     ear,     nose, 
throat 

8.00,  eye 

Dr.  Wilson. 

8.20 

Dr.  Gordon. 
Chair. 

Strict  adlierence  to  tlae  "  Liberty  motor  "  scheme  of  Physical  Examining  Units 
results  in  the  greatest  possible  saving  of  time  and  labor  on  the  part  of  those 
constituting  the  unit.  With  properly  developed  team  and  individiial  technique, 
a  seven-man  team  can  complete  careful  examination  of  20  applicants  at  a 
cost  of  not  to  exceed  55  to  75  minutes  for  any  individual  on  the  team.  Punc- 
tuality is  the  keystone  of  such  an  organization. 

jJlank  609.] 

Figure  1. 

[First    page.] 

PHYSICAL  EXAMINATION  OF  APPLICANTS  FOR  DETAIL  IN  THE  AVIA- 
TION SECTION,  SIGNAL  CORPS. 

Place  

Date    

Name^ • 

Rank  and  organization  or  status 

].  History  of  previous  or  present  eye  trouble 


Stereoscopic  vision,  if  stereoscope  is  available 

Ocular  movements 

Pupillary  reactions 

Direct.                Consensual. 
Right  eye 


Accommodation. 


Left  eye. 


5.  Intraocular   tension.. 


f  Right 


'{Left 
6.  Any  visible  lesion  of  eyes?— 


fRight- 

iLeft— 
7.   (a)  Is  ocular  nystagmus  present? 


(&)  Does  ocular  nystagmus  occur  when  eyes  are  turned  easily  to  one  side? 

(c)  Does  ocular  nystagmus  occur  when  eyes  are  turned  to  the  extreme  side? 

fRight 

8.  Field  of  vision—] 


AIR  SERVICE  MEDICAL.  59 

9.  Color  vision  

10.  Muscle  balance,  at  20  feet  (use  pliorometer  or  maddox  rod)  : 

Hyperphoria  

Esophorln    

Bxoplioria   ^ 

[Second  page.] 

11.  Visual   acuity: 

fllight 

(a)  Distance,  at  20  feet— < 

[Left 


(6)   Near  point- ■! 


[Right cm.  = 

Left cm.  = 

Right 


Left 


12.  Ophthalmoscopic  findings  (5  per  cent  euphthalmiue  dilatation) 

EAR. 

13.  History  of  ear  trouble : 

(o)  Ever  have  ringing  or  buzzing  in  either  ear,  earache,  discharge,  or 
mastoiditis?    

(6) Ever  have  attacks  of  dizziness  from  any  cause? 

(c)Ever  been  seasick? If  so,  how  often? and 

how  long  does  it  last? 

(d)  Ever  had  a  severe  injury  to  head? 

fRight   

14.  (a)Appearance  of  external  auditory  canal— < 

[Left    


fRight   

(&)  Appearance  of  membrani  tympani < 

[Left    

(c)  Hearing  (watch, No.  inches;      1  Right,  /40  (40/40 normal) feet. 

whisper.  No.  of  feet) JLeft,  /40  (40/40  normal) feet. 

NASO-PHARYNX. 

15.  Condition  of  nares  (if  obstructed,  state  degree,  character,  and  cause)  : 

Right   

Left    

16.  Condition  of  tonsils  and  history  of  attacks  of  tonsillitis : 

Right 

Left    

17.  Presence  of  adenoids  

18.  Condition  of  eustachian  tubes  (if  obstructed  state  character  and  degi-ee) 

after  politzeration  or  per  catheter ^ 

19.  Sttitic  tests,  horizontal  plane   (shoes  removed).     Applicant  to  stand  with 

knees  pressed  back,  arms  loose  by  side  of  body,  eyes  closed,  inner  mar- 
gins of  feet  touching  each  other 


60  AIR  SERVICE  MEDICAL. 

[TMrd  page.] 

20.  Equilibrium  (vestibular)  Head  tilted  forward  30  degrees.  Eyes  closed. 
Rotation  nystagmus  normal  26  seconds,  a  variation  of  10  seconds  al- 
lowable. 

(a)  Right:  Applicant  to  be  turned  toward  his  right,  10  turns  in  ex- 
actly 20  seconds,  horizontal  nystagmus  to  left  for 

seconds. 
Left:  Applicant  to  be  turned  toward  his  left,  10  times  in  ex- 
actly 20  seconds,  horizontal  nystagmus  to  right  for 

seconds. 
( & )  Pointing  tests : 

(1)  Before  turning — Right  arm ,  left  arm 

(2)  After  turning  10  times  in  10  seconds  to  right — Right  arm 
,  left  arm 

(3)  After  turning  10  times  in  10  seconds  to  left — Right  arm 

,  left  arm 

(c)  Falling  tests: 

(1)  Turn  to  right,  5  turns  in  10  seconds — Falls  to 

(2)  Turn  to  left,  5  turns  in  10  seconds — Falls  to 


21.  Dynamic  tests,  horizontal  plane  (eyes  closed  and  shoes  removed).  Appli- 
cant to  walk  on  feet  flat  to  floor  straight  forward  20  feet  and  back  to 
point  of  starting.  Repeat  if  necessary.  Slight  variation  allowable  if  not 
constant  


22.  Height inches.    Weight pounds. 

23.  Chest  measurement:  Expiration inches;  inspiration. 

inches. 

24.  Respiratory  system 

25.  Bones  and  joints 

26.  Skin 

27.  Nervous  system 

28.  Vascular  system 

(a)  Pulse:  Rate per  minute;  quality 

(&)  Condition  of  arteries 

(c)  Blood  pressure;  Systolic ;  diastolic 

id)  Heart 

(e)   Veins  

(/)  Hemorrhoids 

29.  Digestive  system 

30.  Hernia 

31.  Genito-urinary  system 

32.  Urinalysis: 

Specific  gravity 

Reaction   

Casts 

Sugar  

Albumen   

33.  Is  the  candidate  physically  qualified  for  aeronautical  duty? 


AIE  SERVICE   MEDICAL.  61 

[Back  of  form.] 

INSTRUCTIONS. 

The  following  instructions  will  govern  the  Medical  Officers  making  the  ex- 
amination : 

EYE  DETEEMINATION. 

1.  Question  the  candidate  carefully  regarding  previous  or  present  eye  trouble, 
use  of  glasses,  headaches,  lacrymation,  scotoma,  and  photophobia ;  also  diplopia 
(musc£e  volitantes  panorama  symptoms),  glaucomatous  symptoms,  night  blind- 
ness or  asthenopia  when  not  wearing  correcting  lenses.  Any  one  of  the  latter 
group  disqualifies  and  also  of  the  former  group  if  marked.    Note  findings. 

2.  Stereoscopic  vision  is  the  ability  to  appreciate  depth  and  distances  by 
means  of  binocular  single  vision.  Objects  printed  on  the  test  cards  furnished 
for  use  with  the  stereoscope  are  drawn  to  scale,  the  distance  between  correspond- 
ing points  of  similar  objects  are  equal;  between  dissimilar  objects,  unequal. 
They  are  seen  at  different  apparent  depths,  the  result  of  superposition  of  each 
two  similar  images  in  space;  the  less  the  distance  between  the  objects,  the 
nearer  they  appear  to  the  observer's  eyes,  the  greater  the  distance  between, 
the  farther  away  they  appear.  A  normal  eye  can  appreciate  an  apparent  differ- 
ence in  distance  between  stereoscoped  objects  of  0.01  mm.  Adjust  the  oculars  of 
the  stereoscope  at  their  focal  distance  (15  cm.)  from  the  glass  stage  and  rotate 
by  means  of  the  milled  edge  on  either  ocular  cup  so  that  the  interpupillai-y  dis- 
tance will  be  as  great  or  greater  than  the  distance  between  any  two  similar 
points  of  objects  to  be  stereoscoped.  With  good  illumination,  have  the  candi- 
date name  the  sequence  of  objects  from  front  to  rear  as  he  sees  them  through 
the  stereoscope.  This  should  be  done  readily  and  without  error,  otherwise  it 
is  a  cause  for  rejection. 

3.  Ocular  movements  are  tested  roughly  by  requiring  both  eyes  of  the  candi- 
date to  be  fixed  on  the  examiner's  finger,  which  is  carried  from  directly  in 
front  to  the  right,  to  the  left,  up,  and  down.  The  movements  of  each  eye  must 
be  regular  and  identical. 

4.  Pupillary  reactions  should  be  regular  and  equal  in  each  eye  when  respond- 
ing to  (1)  direct  and  (2)  indirect  light  stimulation  and  (3)  to  accommodation. 
Face  the  candidate  and  place  a  card  as  a  screen  before  both  eyes.  Uncover 
one  eye  after  a  short  interval  and  allow  light  to  shine  in  this  eye.  The  result- 
ing contraction  of  the  iris  of  this  eye  is  called  direct.  Repeat,  but  now  observe 
the  shaded  eye.  This  reaction  is  indirect  or  consensual  of  the  shaded  eye.  Re- 
peat for  the  other  eye. 

With  both  the  candidate's  eyes  open  and  uncovered,  have  him  /?ar  on  a  pencil 
held  a  few  inches  directly  in  front  of  him.  Bring  the  pencil  toward  him  until 
it  nearly  touches  his  nose.  Both  irides  will  contract,  which  is  called  the 
reaction  to  accommodation. 

5.  Intraocular  tension  is  tested  roughly  by  palpation.  The  candidate  look- 
ing downward,  palpate  the  eye  through  the  upper  lid  with  the  index  finger 
of  each  hand,  and  compare  the  teijsion  with  the  other  eye  and  with  an  eye 
believed  to  be  normal.    If  not  normal  it  is  a  cause  for  rejection. 

6.  Any  visible  lesion  of  the  eye  is  determined  by  having  the  candidate  near 
to  and  facing  a  well-illuminated  window  and  assisted  by  the  use  of  a  hand  lens. 
The  eyes  should  be  free  from  disease,  congenital  or  acquired,  such  as  lesions 
of  the  cornea,  iris,  or  lens,  including  affections  of  surrounding  structures  such  as 
pathological  conditions  of  the  lachrymal  apparatus,  conjunctival  deformities, 
or  any  other  affection  which  would  tend  to  cause  blurring  of  vision  if  the  eyes, 
unprotected  by  glasses,  were  exposed  to  wind  or  other  unfavorable  atmos- 
pheric conditions. 


62  AIR  SERVICE  MEDICAL. 

7.  Ocular  nystagmus  is  determined,  and  if  it  is  rhythmical  and  occurs — (a) 
and  (&) — on  looking  straight  ahead  or  laterally,  40  degrees  or  less,  it  is  a 
cause  for  rejection. 

(c)  Spontaneous  ocular  7iystagmus  produced  by  extreme  lateral  sight,  50 
degrees  or  more,  is  not  a  cause  for  rejection,  as  it  is  found  in  the  normal  in- 
dividual. It  is  usually  manifested  by  a  few  oscillating  lateral  movements, 
never  rotary,  which  appear  when  the  eyes  are  first  fixed  in  extreme  lateral  po- 
sitions. Select  a  scleral  vessel  near  the  corneal  margin  as  a  point  for  ob- 
servation. 

8.  Field  of  vision  is  tested  separately  for  each  eye.  Place  the  candidate  with 
his  back  to  the  source  of  light  and  have  him  fix  the  eye  under  examination 
(the  other  being  covered)  upon  the  examiner's,  which  is  directly  opposite  at 
a  distance  of  2  feet.  The  examiner  then  moves  his  fingers  in  various  directions 
in  a  plane  midway  between  himself  and  the  candidate,  until  the  limits  of  in- 
direct vision  are  reached.  The  examiner  thus  compares  the  candidate's  field 
of  vision  with  his  own  and  can  thus  roughly  estimate  whether  normal  or  not. 
A  restricted  field  of  vision  should  be  confirmed  by  the  use  of  a  perimeter,  as 
it  would  then  be  a  cause  for  rejection. 

9.  Color  vision  should  be  normal  for  red  and  green.  A  Jenning's  test  set  is 
preferred.  If  not  available,  then  select  a  skein  of  any  shade  of  red  or  green 
worsted  and  have  the  candidate  select,  in  separate  piles,  all  skeins  containing 
red  or  green.  If  confusion,  colored  lights  at  20  feet  should  be  used  as  a  test 
before  rejecting. 

10.  Muscle  balance  at  20  feet. — A  phorometer,  with  spirit  level,  maddox  rod, 
and  rotary  prism  attached,  should  be  used  to  determine  the  presence  or  absence 
of  a  muscular  imbalance.  Adjust  the  phorometer  close  to  and  in  front  of 
the  candidate's  eyes,  at  20  feet  distance  from  a  point  of  light  10  mm.  in  diameter 
on  the  same  level  with  eyes.  Darken  the  room  and  arrange  the  prisms  so  that 
their  bases  are  situated  inward ;  two  images  of  the  light  will  then  be  seen  dis- 
placed laterally.  If  on  a  level,  there  is  a  normal  balance  of  the  vertically 
acting  extrinsic  eye  muscles  or  orthophoria ;  if  not  on  the  same  level,  there  is 
vertical  imbalance  or  hypei-phoria ;  left  if  the  left  image  is  below,  right  hyper- 
phoria if  the  right  image  is  below.  Read  off  on  the  scale  the  amount  necessary 
to  bring  the  images  on  the  same  level. 

Repeat  the  tests  with  the  prisms,  one  up  and  one  down.  If  the  images  now 
are  directly  above  each  other  there  is  no  lateral  imbalance,  but  if  laterally 
displaced  and  on  the  same  side  with  the  eye  seeing  each  image,  there  is  homony- 
mous diplopia  due  to  a  lateral  imbalance  called  esophoria.  If  the  images  are 
crossed  there  is  exophoria.  Read  off  on  the  scale  the  amount  necessary  (prism 
diopters)  to  bring  them  in  the  same  vertical  meridian.  If  not  more  than  one 
(1)  degree  of  hyperphoria  and  more  than  two  (2)  degrees  of  esophoria  or 
exophoria,  the  test  is  satisfactory. 

11.  Visual  acuity. —  (a)  Acuity  for  distance  tested  at  20  feet  from  a  well 
illuminated  Snellen  test  card,  if  less  than  20/20  in  either  eye,  tested  separately, 
disqualifies. 

(&)  Near  point,  or  acuity  for  near  vision,  is  determined  separately  for  each 
eye  by  requiring  the  candidate  to  read  in  a  good  light  the  Jaeger  No.  1  test 
type,  first  gradually  bringing  the  card  toward  the  uncovered  eye  until  the 
nearest  point  to  the  eye,  at  which  the  test  type  still  remains  distinct,  is  reached. 
The  distance  of  this  point  from  the  anterior  surface  of  the  cornea,  measured  in 
centimeters,  is  the  near  point.  Greater  than  11  cm.  at  20  years  of  age,  greater 
than  13  cm.  at  25  years  of  age,  or  greater  than  15  cm.  at  30  years  of  age, 
disqualifies. 


AiE  SERVICE  Medical.  63 

12.  Ophthalmoscopic  findings. — Drop  one  drop  of  a  5  per  cent  solution  of 
euphthalmiue  in  eacli  eye.  Have  the  candidate  keep  his  eyes  closed.  After  15 
minutes  repeat  the  drops,  then  examine  15  minutes  later.  A  pathological  con- 
dition of  the  fundus,  active  or  quiescent,  is  cause  for  rejection. 

EAB  DETEBMINATION. 

13.  Abnormalities  are  cause  for  rejection. 

14.  Hearinp  should  be  norn^al  for  each  ear.  To  determine  this  both  the 
whisper  and  watch  tests  are  used.  After  examining  both  external  auditory 
canals  and  membrani  tympani  by  means  of  a  speculum  and  a  good  light  (first 
removing  any  wax  if  present)  for  abnormalities  such  as  small  and  tortuous 
opening,  presence  of  pus,  perforation,  scars,  retraction,  or  other  evidence  of 
past  or  present  inflammation,  which  are  causes  for  rejection,  the  candidate  is 
required  to  stand  at  20  feet  from  the  examiner  and  facing  away  from  him.  An 
assistant  closes  the  ear  not  under  examination  with  his  moistened  index  finger 
pressed  firmly  into  the  external  auditory  meatus.  The  examiner  facing  the 
bacli  of  the  candidate  exhales  and  then,  with  his  residual  air,  tvhispers  numbers, 
words,  or  sentences  which  the  candidate  should  repeat.  The  other  ear  will  then 
be  tested  in  a  similar  manner.  If  unable  to  hear,  the  examiner  will  approach 
until  the  candidate  does  hear,  the  distance  being  recorded  in  feet.  If  less  than 
20  feet  it  is  a  cause  for  rejection.    A  quiet  room  is  essential. 

The  icatch  test  is  preferably  made  with  a  loud-ticking  watch  such  as  the 
ordinary  Ingersoll  which,  while  variable,  should  be  heard  at  about  40  inches. 
Any  watch  used  should  have  been  previously  tried  out  on  at  least  five  normal 
persons  and  the  distance  heard  made  a  matter  of  record.  The  number  of  inches 
in  distance  heard  by  the  candidate,  eyes  closed  and  opposite  ear  occluded,  is 
taken  as  the  numerator  and  the  distance  the  watch  should  be  heard  as  the  de- 
nominator.   This  should  be  the  equivalent  of  40/40,  otherwise  disqualifies. 

NASO-PHAEYNX. 

15  to  18.  This  region  should  be  carefully  examined.  If  defects  can  be 
removed  by  operation,  this  should  be  required  prior  to  completing  the  examina- 
tion.   If  nonoperable  or  operation  refused,  it  is  a  cause  for  rejection. 

STATIC  TESTS, 

19.  The  position  should  be  maintained  for  one  minute  without  marked 
swaying.    Eyes  closed. 

EQUILIBBIUM    (VESTIBULAR  TESTS). 

20.  The  nystagmus,  past-pointing  and  falling,  after  turning,  are  tested. 
The  turning  chair  must  have  a  head-rest  which  will  hold  the  head  30  degrees 
forward,  a  foot-rest,  and  a  stop-pedal. 

(a)  Nystagmus. — Head  30  degrees  forward  ;  turn  candidate  to  the  right,  eyes 
closed,  10  times  in  exactly  20  seconds.  The  instant  the  chair  is  stopped,  click 
the  stop-watch ;  candidate  opens  his  eyes  and  looks  straight  ahead  at  some  dis- 
tant point.  There  should  occur  a  horizontal  nystagmus  to  the  left  of  26  sec- 
onds duration.  Candidate  then  closes  his  eyes  and  is  turned  to  the  left;  there 
should  occur  a  horizontal  nystagmus  to  the  right  of  26  seconds  duration.  The 
variation  of  S  seconds  is  allowable. 

(h)  Pointing. —  (1)  Candidate  closes  eyes,  sitting  in  chair  facing  examiner, 
touches  the  examiner's  finger  held  in  front  of  him,  raises  his  arm  to  perpen- 
dicular position,  lowers  the  arm,  and  attempts  to  find  the  examiner's  finger. 
I'irst  tlie  right  arm;  then  the  left  arm.  The  normal  is  always  able  to  find  the 
§9118—19 5 


64  AIK  SERVICE  MEDICAL. 

finger.  (2)  The  pointing  test  is  again  repeated  after  turning  to  the  right,  10 
turns  in  10  seconds.  During  the  last  turn  the  stop-pedal  is  released  and  as  the 
chair  comes  into  position,  it  becomes  loclied.  The  right  arm  is  tested,  then  the 
left,  then  the  right,  then  to  the  left  until  he  ceases  to  past-point.  The  normal 
will  past-point  to  the  right  3  times  with  each  arm.  (3)  Repeat  pointing  test 
after  turning  to  the  left. 

(c)  Falling. — Candidate's  head  is  inclined  90  degrees  forward.  Turn  to  the 
right,  5  turns  in  10  seconds.  On  stopping,  candidate  raises  his  head  and  should 
fall  to  the  right.  This  tests  the  vertical  semicircular  canals.  Turn  to  the  left, 
head  forward  90  degrees ;  on  stopping,  the  candidate  raises  his  head  and  should 
fall  to  the  left.    Unless  each  test  is  normal,  it  is  a  cause  for  rejection. 

Special  Regulations  No.  50  Aviation  Section,  Signal  Corps,  1917,  War  De- 
partment, and  Circular  No.  2,  War  Department,  November  1,  1916,  and  the 
physical  requirements  of  recruits  will  govern  22  to  32  inclusive. 


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CHAPTER  IV. 

SIGNIFICANCE  OF  THE  TESTS  COMPRISING  THE 
PHYSICAL  EXAMINATION. 


Although  it  has  been  found  that  the  details  of  the  examination 
given  on  the  back  of  Form  609  are  ample  for  the  purposes  of  exam- 
iners who  have  long  been  accustomed  to  work  in  Physical  Examining 
Units,  experience  has  shown  that  a  more  detailed  description  of  these 
tests  is  of  value  to  those  who  are  not  so  familiar  with  the  work. 

EYE. 

HISTORY  or  PRESENT  OR  PREVIOUS  EYE  TROUBLES. 

In  the  early  days  of  the  work  of  the  Examining  Units,  when  history 
of  the  asthenopic  symptoms  was  presented,  the  question  of  refraction 
was  considered  a  most  important  one.  Indeed  on  the  first  examina- 
tion chart  one  of  the  requisites  was  an  accurate  determination  of  the 
refractive  error  of  the  eyes  under  a  cycloplegic.  This  was  done 
because  it  had  been  found  on  many  occasions  during  active  flying 
that  men  with  latent  hyperopia  lost  their  power  of  accommodation 
and  the  hyperopia  became  manifest.  This  condition  naturally 
caused  an  impairment  of  the  visual  acuity. 

After  a  short  time,  however,  it  was  decided  that  if  a  careful 
analysis  was  made  by  the  examiner  of  the  relations  between  age, 
vision  at  infinity,  the  near-point  of  accommodation,  and  the  muscle 
balance,  this,  together  with  the  estimate  of  the  refraction  with  the 
ophthalmoscope,  would  be  sufficiently  accurate  for  all  purposes  and 
the  complete  refraction  was  omitted. 

The  applicant  is  also  questioned  as  to  the  occuiTence  of  headache, 
whether  they  were  ever  migranous  in  character,  and  if  so  whether 
they  were  accompanied  by  hemianopsia  or  scotomata.  If  either  of 
the  latter  were  likely  to  appear  it  was  considered  advisable  that  the 
applicant  be  disqualified.  A  history  of  photophobia  is  important. 
Diplopia  and  night-blindness  are  two  conditions  which  are  so 
obviously  disqualifying  that  they  need  no  further  comment. 

STEREOSCOPIC   VISION. 

Three  cards  similar  in  appearance,  but  with  differing  arrangements 
of  numbers  are  used.  The  transferring  of  information  from  ap- 
plicant to  applicant  concerning  the  order  of  numbers  on  these  cards 
is  impossible. 

65 


66  AIE  SEEVICE   MEDICAL. 

It  has  happened  that  applicants  have  been  rejected  who  possessed 
good  stereoscopic  vision,  the  fault  being  in  the  way  the  test  was  ap- 
plied. In  some  cases  time  and  patience  are  needed  to  teach  the  ap- 
plicant what  he  is  expected  to  do. 

Since  stereoscopic  vision  is  essentially  a  binocular  act  it  is  impor- 
tant to  make  sure  that  the  applicant  is  actually  seeing  the  pictures 
with  both  eyes  simultaneously.  It  is  possible  to  have  simultaneous 
binocular  vision  without  stereoscopic  vision  but  it  is  not  possible  to 
have  stereoscopic  vision  without  both  eyes  fixing  the  object  practically 
simultaneously.  There  are  two  ways  of  telling  whether  he  is  using 
both  eyes,  subjective  and  objective. 

The  subjective  usually  suffices.  While  the  applicant  is  holding  the 
instrument  in  the  proper  position  with  the  headrest  touching  or 
nearly  touching  the  forehead  and  is  trying  to  see  the  pictures,  the 
card  being  at  about  the  middle  of  the  slide,  you  cover  first  one  lens 
and  then  the  other  with  a  card  and  ask  him  if  he  sees  the  particular 
picture  he  is  looking  at  about  equally  well  with  each  eye.  If  so, 
then  when  the  card  is  removed  he  should  either  fuse  or  see  double 
or  suppress  one  image.  If  he  fuses  he  will  detect  the  stereoscopic 
separation  in  space  of  the  objects  depicted  on  the  card.  Show  him 
how  to  improve  the  focus  by  sliding  the  card  forward  and  back 
but  advise  him  to  keep  it  as  far  away  as  is  consistent  with  clearness. 
If  you  suspect  that  he  is  suppressing  try  the  objective  test.  Have 
him  hold  the  instrument  a  few  inches  away  from  the  face  so  that 
you  can  watch  his  eyes  and  by  covering  first  one,  then  the  other,  in 
the  same  way  that  is  done  when  applying  the  Duane  cover  test,  you 
can  see  whether  there  is  a  movement  of  redress  showing  that  one  eye 
was  not  fixing  while  the  other  was.  You  must  start  with  both  his 
eyes  uncovered  and  then  interpose  a  card  before  the  eye  that  you 
think  is  correctly  fixing,  while  you  watch  the  uncovered  eye.  If  it 
was  properly  fixing  it  will  not  move  but  will  continue  to  fix  as  be- 
fore. It  is  essential  that  each  eye  be  looking  at  the  same  object; 
select  one,  say  the  middle  one  of  the  bottom  row  and  by  covering 
first  one  eye  and  then  the  other  assure  yourself  that  the  instrument  is 
being  held  so  that  each  eye  can  see  the  required  picture. 

Having  determined  that  both  eyes  are  fixing  the  same  object  move 
the  instrument  gradually  nearer  and  see  if  he  can  not  fuse  them. 

It  may  be  necessary  to  move  the  stereoscope  forward  and  back 
several  times  before  he  succeeds. 

OCULAR  MOVEMENTS. 

Ocular  movements  are  tested  roughly  by  requiring  both  eyes  of 
the  candidate  to  be  fixed  on  the  examiner's  finger,  which  is  carried 
from  directly  in  front  to  the  right,  to  the  left,  up,  and  down.  The 
movements  of  each  eye  must  be  regular  and  identical. 


1    '      1     '     >      .    ,    >     1      ,  ',' 


CONSENSUAL   PUPILLARY   REACTION. 

By  shading  one  eye  from  the  Hght  and  then  covering  and  uncovering  the  other  eve,  the  pupil  of  the 
eye  that  IS  shaded  will  be  seen  to  dilate  and  then  contract  in  a  degree  approximating  the  dilatation 
and  contraction  of  the  uncovered  eye.    This  is  called  the  consensual  refle.x  and  indicates  normal 
conaection  between  the  fibers  of  the  two  optic  nerves. 
67b-l 


TAKING  THE  INTRAOCULAR  TENSION  OF  THE  EYE. 


Intraocular  tension  is  tested  roughly  by  palpation.  The  candidate  looking  downward,  palpate 
the  eye  through  the  upper  lid  with  the  index  finger  of  each  hand,  and  compare  the  tension  with  the 
other  eye  and  with  an  eye  believed  to  be  normal.    If  not  normal  it  is  a  cause  for  rejection. 

67b-2 


EXAMINED  FOR  EXTERNAL  DISEASES  OF  THE  EYE. 


67b-3 


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67b-4 


AIR  SERVICE   MEDICAL.  6T 

PUPILLARY  REACTIONS. 

Pupillary  reactions  should  he  regular  and  equal  in  each  eye  when 
responding  to  (1)  direct  and  (2)  indirect  light  stimulation  and  (3) 
to  accommodation.  Face  the  candidate  and  place  a  card  as  a  screen 
before  both  eyes.  Uncover  one  eye  after  a  short  interval  and  allow 
light  to  shine  in  this  eye.  The  resulting  contraction  of  the  iris  of 
this  eye  is  called  "  direct."  Repeat,  but  now  observe  the  shaded  eye. 
This  reaction  is  indirect  or  consensual  of  the  shaded  eye.  Repeat 
for  the  other  eye. 

With  both  the  candidate's  eyes  open  and  uncovered,  have  him  fix  on 
a  pencil  held  a  few  inches  directly  in  front  of  him.  Bring  the  pencil 
toward  him  until  it  nearly  touches  his  nose.  Both  irides  will  con- 
tract, which  is  called  the  reaction  to  accommodation. 

EXTERNAL  OCULAR  EXAMINATION. 

Intraocular  tension  is  tested  roughly  by  palpation.  The  candi- 
date looking  downward,  palpate  the  eye  through  the  upper  lid  with 
the  index  finger  of  each  hand,  and  compare  the  tension  with  the 
other  eye  and  with  an  eye  believed  to  be  normal.  If  not  normal  it 
is  a  cause  for  rejection. 

Any  visible  lesion  of  the  eye  is  determined  by  having  the  candidate 
near  to  and  facing  a  well-illuminated  window  and  assisted  by  the 
use  of  a  hand  lens.  The  eyes  should  be  free  from  disease,  congenital 
or  acquired,  such  as  lesions  of  the  cornea,  iris,  or  lens,  including 
affections  of  surrounding  structures  such  as  pathological  conditions 
of  the  lachrymal  apparatus,  conjunctival  deformities,  or  any  other 
affection  which  would  tend  to  cause  blurring  of  vision  if  the  eyes, 
unprotected  by  glasses,  were  exposed  to  wind  or  other  unfavorable 
atmospheric  conditions. 

OCULAR  NYSTAGMUS. 

Ocular  nystagmus  is  determined,  and  if  it  is  rythmical  and  oc- 
curs (a)  and  (6) — on  looking  straight  ahead  or  laterall}'  40°  or  less, 
it  is  cause  for  rejection. 

FIELD    OF    VISION. 

Field  of  vision  is  tested  separately  for  each  eye.  Place  the  candi- 
date with  his  back  to  the  source  of  light  and  have  him  fix  the  eye 
under  examination  (the  other  being  covered)  upon  the  examiner's 
which  is  directly  opposite  at  a  distance  of  2  feet.  The  examiner 
then  moves  his  fingers  in  various  directions  in  a  plane  midway  be- 
tween himself  and  the  candidate,  until  the  limits  of  indirect  vision 
are  reached.  The  examiner  thus  compares  the  candidate's  field  of 
vision  with  his  own  and  can  thus  roughly  estimate  whether  normal 


68  "  AIK   SERVICE   MEDICAL. 

or  not.    A  restricted  field  of  vision  should  be  confirmed  by  the  use 
of  a  perimeter,  as  it  would  then  be  a  cause  for  rejection. 

COLOR    VISION. 

The  color  perception  test  is  one  which  may  be  very  widely  mis- 
applied to  the  detriment  of  the  service.  If  a  man  has  definitely  cor- 
rect perception  of  red  and  green  he  is  suitable  for  this  service.  There 
are  marginal  colors  represented  on  the  Jennings  test  which  are  the 
source  of  some  confusion  and  have  been  not  infrequently  the  basis 
of  disqualification  of  a  good  applicant.  It  should  be  definitely  as- 
certained that  a  man's  red  and  green  perceptions  are  normal  by  the 
use  of  the  Jennings'  test,  but  the  disqualifying  of  otherwise  desirable 
applicants  because  they  have  punched  some  lavenders  or  lilacs  for 
rose,  for  instance,  should  not  occur. 

A  high  standard  of  color  vision  has  been  demanded  of  prospective 
fliers;  but  its  importance  is  demonstrated  when  it  is  realized  that 
normal  color  vision  is  required  not  only  for  the  recognition  of  sig- 
nals but  of  the  insignia  on  the  planes.  The  detection  of  the  color 
of  the  ground  where  freshly  turned  earth  may  be  the  only  evidence 
of  new  entrenchments  and  landing  places,  may  be  simply  a  differen- 
tiation of  tints  of  brown  and  green  and  is  all  that  the  pilot  has  to 
suggest  to  him  the  type  of  ground  over  which  he  is  observing. 

MUSCLE   BALANCE. 

The  first  detail  which  should  be  noted  is  the  age  of  the  applicant ; 
the  next  is  the  distance  visual  acuity,  which  should  be  20/20  in  each 
eye  (and  by  20/20  it  is  safe  to  mean  that  a  man  has  full  normal 
vision,  not  necessarily  that  he  read  without  one  mistake  every  letter 
in  the  ordinary  20-foot  line ;  a  man  who  misreads  one  or  two  letters 
in  the  20-foot  line  and  compensates  for  such  misreading  by  reading 
correctly  one  or  two  letters  in  the  next  smaller  line  can  be  considered 
to  have  full  normal  vision ;  in  such  a  case  full  normal  vision  should 
be  expressed  by  the  term  "  20/20  ") . 

The  third  point  in  this  chain  of  evidence  as  to  the  ocular  desira- 
bility of  the  applicant  is  the  near-point  of  accommodation,  and  the 
fourth  point  is  the  muscle  balance  test.  Muscle  balance  constitutes 
one  of  the  greatest  sources  of  exclusion  from  the  service  of  any  of  the 
"  609  "  qualifications.  The  attitude  of  the  examiner  concerning  muscle 
balance  should  be  as  follows :  As  long  as  the  applicant  has  a  muscle 
balance  which  is  commensurate  with  his  refraction,  and  his  refrac- 
tion is  not  of  a  nature  to  endanger  the  service,  he  should  not  be  dis- 
qualified. For  example,  an  applicant,  age  22,  vision  20/20 — 20/20, 
near-point  of  right  eye  12  cm.,  left  eye  13  cm.,  has  manifestly  some  de- 
gree of  latent  hyperopia,  cither  simple  or  compound.    This  entails 


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68b-l 


TESTING  THE  MUSCLE  BALANCE  OF  THE  EYE. 

The  muscle  balance  of  the  eye  must  he  in  perfect  alignment.  In  other  words,  there  must  be  no 
latent  tendency  for  the  eye  to  turn  up  or  down  or  in  or  out.  If  there  is,  the  aviator  may  see 
double  and  thus  endanger  his  Ufe  at  a  critical  moment. 

681>-2 


AIR  SERVICE   MEDICAL.  69 

the  using  up  of  a  certain  amount  of  his  total  available  accommoda- 
tion in  the  act  of  seeing  with  20/20  acuity  at  the  distance.  If  he 
has  applied  a  certain  amount  of  accommodative  effort  in  seeing 
20/20 — 20/20,  he  has  at  the  same  time  applied  a  commensurate  amount 
of  convergence,  inasmuch  as  accommodation  and  convergence  are 
functions  indissoluble^  linked  together.  Therefore,  if  such  a  man 
shows  4^°  to  5^°  of  esophoria  he  is  not  nec'essarily  an  unsafe  indi- 
vidual for  our  service. 

The  fourth  point  is  the  test  of  convergence  and  divergence.  Con- 
vergence is  tested  by  measuring  the  near  point  of  convergence.  A 
less  valuable  subsidiary  test  is  the  prism  convergence  tested  at  20 
feet.  The  divergence  is  found  by  measuring  prism  divergence  at  20 
feet.    Lastly,  test  the  power  of  overcoming  prisms  up  and  down. 

In  interpreting  your  findings  the  muscle  balance  should  always  be 
considered  in  the  light  of  both  the  refraction  and  the  convergence, 
divergence,  and  sursumvergence  tests. 

Thus,  an  applicant  whose  near  point  is  farther  away  than  normal 
for  his  age — say  14  cm.  at  21  years  of  age  when  it  should  be  about 
11  cm. — is  probably  hypermetropic  though  it  might  be  that  his  ac- 
commodation is  subnormal.  If  hypermetropia  is  suspected,  the 
question  may  be  settled  by  direct  ophthalmoscopy,  if  you  have  ac- 
quired facility  in  measuring  the  refraction  say  to  1  or  1^  D  in  that 
way,  or  by  the  fogging  test.  This  is  applied  by  placing  +2  sph. 
over  both  eyes.  If  his  vision  is  not  greatly  reduced,  it  is  because  he 
is  hypermetropic. 

Now,  if  he  is  hypermetropic  some  esophoria  is  to  be  expected  and 
even  as  much  as  5°  should  not  cause  concern  provided  that  he  has 
good  divergence  as  tested  with  prisms,  say  5°  or  more.  Esophoria 
due  to  convergence  excess  is  not  disqualifying  if  there  is  good  power 
of  divergence.  Esophoria  due  to  divergence  weakness  is  decidedly 
disqualifying.    Such  a  case  would  probably  not  have  hypermetropia. 

Following  up  this  line  of  thought  it  is  but  a  step  to  visualizing 
what  might  happen  to  such  an  individual  under  stress  of  fatigue  such 
as  he  may  reasonably  expect  to  encounter  in  active  service.  When  a 
sufficient  degree  of  fatigue  shall  have  been  reached  by  the  applicant 
during  a  flight  and  combat,  his  ability  to  maintain  the  amount  of 
accommodative  contraction  necessary  to  keep  his  visual  acuity  up  to 
20/20  in  each  eye  will  come  to  an  end.  He  will  then  find  his  distance 
visual  acuity  dropping  perhaps  to  20/30,  20/40,  or  even  20/50  in  rela- 
tively high  cases  of  latent  hyperopia.  What  happens  to  his  muscle 
balance  at  such  a  time?  Will  he  find  himself  also  tending  to  become 
diplopic?  In  all  probability  not,  as  with  the  relaxation  of  his  ac- 
connnodation  there  can  be  expected  a  commensurate  diminution  in 
his  convergence,  and  at  that  time,  instead  of  showing  five  and  one- 
half  degrees  of  esophoria,  he  would  show  less.     On  the  other  hand. 


70  AIB  SERVICE  MEDICAL. 

let  lis  suppose  that  such  an  indiA'idual  had  shown  two  degrees  of  ex- 
ophoria;  with  the  onset  of  his  fatigue  relaxation  of  accommodation 
he  would  probably  experience  a  commensurate  amount  of  decrease  in 
his  convergence,  resulting  in  an  increase  in  his  already  existent  ex- 
ophoria,  and  he  would  jfind  with  his  decreased  visual  acuity  an 
amount  of  exophoria  which  would  almost  certainly  determine  the 
onset  of  diplopia,  as  man  is  very  much  less  able  to  maintain  fusion 
in  the  presence  of  a  sudden  increase  in  divergence  than  he  is  in  the 
presence  of  an  increase  in  convergence.  It,  therefore,  seems  impor- 
tant to  standardize  the  method  of  attaining  a  decision  as  to  the  ocular 
desirability  of  the  applicant  in  each  case  along  the  lines  indicated, 
namely:  take  into  consideration  (1)  age,  (2)  distance  acuity,  (3) 
near  point  of  accommodation  and  convergence,  (4)  muscle  balance, 
and  (5)  duction  tests,  beginning  with  prism  divergence,  minimum 
five  degrees.  In  certain  cases  of  fatigue,  spasm  of  accommodation 
and  consequent  increase  in  convergence  must  be  expected.  The 
toxins  of  fatigue  have  been  determined  to  be  responsible  for  this 
type  of  ciliary  spasm.  Their  presence  in  the  circulation  gives  evi- 
dence of  a  more  extreme  stage  of  fatigue  than  that  in  which  is  found 
fatigue-relaxation,  and  should  such  a  degree  of  fatigue  be  reached  it 
is  quite  true  that  crossed  diplopia  may  constitute  the  chief  symptom. 
Nevertheless,  of  the  two  conditions  it  is  safe  to  assume  that  ciliary 
spasm  with  crossed  diplopia  will  occur  with  much  less  frequency, 
and  inasmuch  as  it  is  impossible  to  take  steps  which  will  insure 
against  both,  it  is  the  part  of  wisdom  to  follow  a  plan  which  promises 
to  prevent  the  one  which  is  apt  to  occur  most  easilj'^  and  frequently. 
As  some  young  hyperopes  of  high  degree  are  able  to  maintain  20/20 
acuity  in  the  absence  of  fatigue,  an  additional  procedure  of  great 
value  in  arriving  at  a  determination  of  disqualifying  degrees  of  hy- 
peropia is  the  fogging  test  with  a  +  2.00  sphere.  If  an  applicant  is 
able  to  read  20/20  through  a  -)-  2.00  sphere  it  is  absolutely  certain 
that  his  refraction  is  between  -f-  2.50  and  -f  5.00  or  greater.  Such 
applicants  should  be  absolutely  disqualified. 

VISUAL  ACUITY. 

The  applicant  is  seated  at  a  distance  of  20  feet  from  a  well  illumi- 
nated test  card,  a  trial  frame  or  phorometer  is  properly  adjusted 
to  the  face,  the  left  eye  is  covered,  and  he  is  asked  to  read  the  lowest 
line  possible  on  the  card.  The  standard  was  20/20ths  uncorrected 
vision  in  each  eye  and  the  great  majority  of  the  men  accepted  had 
20/15ths  or  better.  To  many  it  has  seemed  that  the  standard  for 
visual  acuity  is  too  high;  that  the  applicant  might  quite  safely  be 
accepted  with  20/30ths,  or  even  20/40ths,  in  one  eye ;  but  it  has  been 
deemed  advisable  that  the  visual  requirements  should  not  be  markedly 
lowered  as  long  as  a  sufficient  number  of  applicants  were  secured 


rob 


TAKING  NEAR-POINT  WITH  JAEGER'S  TEST  TYPE. 

One  eye  being  covered,  it  is  the  nearest  point  to  the  eye  at  which  the  applicant,  by  forcing  his  vision, 
can  read  the  finest  type  distinctly.  It  shows  whether  or  not  he  is  exceedingly  far-sighlt-d  and  also 
determines  the  tone  of  the  ciliary  muscle  within  the  eye. 

71b-i 


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OPTHALMOSCOnC  EXAMINATION. 

The  fundus  of  the  eye  is  carefully  examined  for  evidences  of  past  or  present  disease  which  may  dis- 
qualify him  even  though  his  direct  vision  be  normal. 

71b-2 


ATB  SERVTCE   MEDICAI..  Yl 

SO  conforming  to  the  present  requirement,  which  is  20/20  in  one  eye 
and  20/20-3  in  the  other. 

In  measuring  the  near-point  of  accommodation,  be  sure  to  make 
it  clear  to  the  applicant  what  he  is  to  decide  for  you.  It  is  the  point 
where  the  test  object  (type  or  Duane  line)  begins  to  blur.  The 
reason  for  this  is  that  as  long  as  it  is  sharp  and  clear-cut  it  is  in  focus, 
but  as  soon  as  it  comes  nearer  than  focus,  which  is  the  near-point, 
it  ceases  to  be  clear-cut  and  begins  to  be  blurry.  However,  it  is  still 
easily  distinguished.  If  you  wait  until  it  is  so  blurry  as  to  be  indis- 
tinguishable, you  will  be  far  inside  the  true  near-point.  Every  ex- 
aminer should  have  a  fairly  exact  knowledge  of  the  near-point,  which 
is  the  normal  average  for  any  given  age,  at  least  for  18  to  45.  If, 
then,  his  findings  in  a  given  case  depart  from  the  average,  some 
explanation  should  be  sought. 

The  most  frequent  explanation  perhaps  will  be  an  error  of  observa- 
tion, next  will  be  a  moderately  nearer  near-point  due  to  extra  good 
(supernormal)  accommodation.  Next  a  moderately  more  remote 
near-point  due  to  hypermetropia,  which  uses  part  of  the  accommo- 
dation for  its  correction,  or  due  to  subnormal  accommodation,  most 
frequent  under  low  oxygen,  not  common  in  healthy  young  men  in 
good  physical  condition. 

OPHTHALMOSCOPIC   FINDINGS. 

The  number  of  men  who  have  been  disqualified  on  the  ophthalmo- 
scopic examination  is  also  unfortunately  large.  During  late  child- 
hood and  adolescence  it  is  not  uncommon  for  the  individual  to  en- 
counter a  transitory  acute  chorioditis  incidental  to  some  systemic  in- 
fection or  dissemination  of  a  focal  infection  the  evidence  of  which 
remains  during  life  in  the  form  of  atrophic  spots  and  clumped  pig- 
ment, but  which  causes  very  little,  if  any,  visual  incapacitation  to  the 
individual.  It  really  constitutes  not  more  than  the  scar  following 
recovery  from  such  a  disease  as  smallpox;  it  does  not  indicate  a 
condition  which  tends  to  recur;  and,  providing  it  has  not  been  de- 
tected in  question  No.  8  or  No.  11,  it  actually  is  no  physical  incapaci- 
tation to  the  individual.  Therefore,  it  is  safe  to  rule  upon  such  find- 
ings that  "  scars  do  not  disqualify."  On  the  other  hand  certain  ap- 
plicants show  acute  and  subacute  recrudescing  chorio-retinitis  in  the 
presence  of  full  normal  vision,  which  condition  is  indubitable  evi- 
dence of  the  existence  somewhere  in  the  body  of  an  active  focus  of 
infection.  In  such  cases,  if  the  focus  of  infection  is  definitely  located 
and  eliminated,  and  the  evidence  is  clear  that  as  a  result  of  such 
elimination  the  chorio-retinitis  is  on  the  wane— in  all  probability 
permanently — such  a  case  should  be  not  disqualified  after  the  lapse 
of  an  adequate  period  of  time  in  which  to  ascertain  that  the  chorio- 
retinitis is  waning.    Such  ocular  manifestations  of  focal  infection  as 


72 


AIE  SERVICE  MEDICAL. 


TEST  TYPES. 


V=^.50D. 


Tbe  fpurt«cDtb  of  Aiipjat  waa  the  day  fijie-i  upon  for  the  eailiop;  of  the 
hrig  Pilrrim,  on  her  YOjape  from  Boston  round  Cape  Horn,  to  the  western 
coast  of  >'orth  America.  Aa  flhe  was  to  get  under  waj  earl^  in  the  after- 
noon I  made  mv  appearance  on  board  at  twelve  oVIock  in  full  sea-rig, 
and  with  my  cbcBt,  cODtalniog  an  outfit  for  o,  ti^o  or  three  years  voyage, 


which  I  bad  undertaten  frcn  a  determination  li  cure,  if  possible,  by  an 
cnLir^  change  of  life,  and  by  a  long  absence  from  bookaandfltudy,  awcak- 
nc33  of  the  eyea  which  had  oblige^l  me  to  give  up'  my  pursuits,  and  which 
no  medical  aid  eeemM  likely  to  cure.  The  change  from  the  tight  dresa 
coat,  silk  cap  and  kid  glovca  of  an  undergraduate  at  Cambridge,  to  t.ho 


V  =  .75  D. 

loose  duck  trousers,  checked  slilrt  and  tarpaulin  hat  of  a  sailor,  though  somewhat  of  a  transfor- 
mation, was  soon  made,  and  I  supposed  that  I  should  pass  very  well  for  a  Jack  tar.  But  it  l.s 
impossible  to  deceive  the  practiced  eye  in  these  matters ;  and  while  I  supposed  myself  to  be 
looking  as  salt  as  Neptune  himself,  I  was,  no  doubt,  known  for  a  landsman  by  every  one  on 
board,  as  soon  as  I  hove  in  sight.    A  sailor  has  a  peculiar  cut  to  his  clothes,  and  a  way  of  wear- 


V  =  l.    D. 

ing  them  which  a  green  hand  can  never  get.  The  trousers,  tight  around  the  hips,  and 
thence  hanging  long  and  loose  around  the  feet,  a  superabundance  of  checked  shirt,  a 
low-crowned,  well-varnished  black  hat,  worn  on  the  back  of  the  head,  with  half  a  fathom 
of  black  ribbon  hanging  over  the  left  eye,  and  a  peculiar  tie  to  the  black  silk  necker- 
chief, with  sundry  other  details,  are  signs  the  want  of  which  betray  the  beginner  at  once. 

V=:1.25  D. 

Beside  the  points  in  my  dress  which  were  out  of  the  way,  doubtless  my  complexioni 
and  hands  would  distinguish  me  from  the  regular  salt,  who,  with  a  sun-browned 
cheek,  wide  step  and  rolling  gait,  swings  his  bronzed  and  toughened  hands  ath wart- 
ships  half  open,  as  though  just  ready  to  grasp  a  rope.  "  "With  all  my  imperfections 

V  =  1.50  D. 

on  my  head,"  I  joined  the  crew,  and  we  hauled  out  into  the  stream  and 
came  to  anchor  for  the  night.  The  next  day  we  were  employed  in  prep- 
aration for  sea,  reeving  and  studding-sail  gear,  crossing  royal  yards, 
putting  on  chafing  gear,  and  takiiig  on  board  our  powder.     On  the 

V  =  1.75  D. 

following  night  I  stood  my  first  watch.  I  remained  awake 
nearly  all  the  first  part  of  the  night,  from  fear  that  I  might 
not  hear  when  I  was  called ;  and  when  I  went  on  deck,  so 
great  were  my  ideas  of  the  importance  of  my  trust,  that  I 

V==2.   D. 

walked  regularly  fore  and  aft  the  whole  length  of  the 
vessel,  looking  out  over  the  bows  and  taffrail  at  each 
turn,  and  was  not  a  little  surprised  at  the  uncon- 
cerned manner  in  which  the  billows  turned  up  their 


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AIE  SERVICE   MEDICAL.  73 

anterior  uveitis  or  so-called  serous  iritis  should  not  be  overlooked 

and  should  be  regarded  as  disqualifying,  unless  strong  evidence  can 

be  brought  to  bear  to  indicate  that  the  source  has  been  permanently 

removed. 

EAR. 

•HISTORY  OF  EAR  TKOUCLE. 

The  answers  to  these  questions  are  designed  in  a  general  way  to 
arrive  at  an  indication  of  any  previous  ear  trouble.  It  is  to  be  taken 
into  consideration  that  very  few  applicants  are  willing  to  admit  the 
history  of  ear  discharge  or  dizziness,  and  conclusions  will  have  to 
be  drawn  from  the  examination  of  the  drumhead  and  subsequent 
hearing  and  rotation  tests. 

It  is  the  universal  experience  that  most  applicants  deny  that  they 
have  ever  been  seasick,  thinking  thereby  to  prove  that  they  would 
be  unaffected  by  the  motion  of  an  aeroplane.  Answers  to  this  ques- 
tion for  that  reason  must  be  taken  with  considerable  allowance.  It 
is  to  be  emphasized  that  it  would  be  improbable  for  a  person  with 
perfectly  normal  ears  not  to  become  seasick  upon  his  first  exposure 
to  a  rough  sea. 

APPEARANCE   OF   MEMBRANA  TrMPANI. 

A  perforation  of  the  drumhead,  unless  transitory,  is  to  be  regarded 
as  a  cause  for  rejection.  If  the  drumhead  is  excessively  thin  and 
scarred,  even  if  the  hearing  is  normal,  it  should  receive  special  con- 
sideration, including  catheter  and  pneumatic  otoscope.  Experience 
has  shown  that  even  in  the  low-pressure  chamber  of  the  laboratory, 
perforations  can  easily  occur  in  such  drums  by  a  rapid  descent. 

Pathological  conditions  of  the  internal  ear  disqualify.  Acute  and 
chronic  disease  of  the  middle  ear  disqualifies,  except  that  reexamina- 
tion after  full  recovery  may  be  made  the  basis  of  subsequent  ac- 
ceptance. Moderately  retracted  drumhead,  loss  of  light  reflexes, 
thickened  drum  membrane,  and  chalk  deposits  do  not  disqualify, 
provided  the  hearing  is  normal.  The  pathology  of  the  drumhead 
is  not  an  index  of  the  hearing  ability.     No  conclusions  can  be  drawn 

without  hearing  tests. 

NASO-PHARYNX. 

CONDITION  OF  THE  NARES. 

This  region  must  be  carefully  examined.  If  defect  can  be  removed 
by  operation,  this  should  be  required  prior  to  acceptance.  If  non- 
operable  or  operation  is  refused,  it  is  a  cause  for  rejection. 

The  question  as  to  what  degree  of  deviation  of  the  septum  demands 
an  operation  is  a  difficult  one  to  answer  and  must  be  left  to  the  ex- 


74"  AIR  SERVICE  MEDICAL. 

perience  of  the  examiner.  One  thing  must  always  be  clearly  borne 
in  mind :  Aside  from  the  straightening  of  an  occlusive  deviation  for 
the  purpose  of  giving  the  applicant  better  air,  resecting  the  septum 
is  not  infrequently  of  great  value  as  a  prophylactic  measure.  The 
majority  of  individuals  who  have  trouble  with  their  ears  are  troubled 
because  of  a  post-nasal  and  Eustachian  tube  catarrh.  Septal  devia- 
tion far  back,  impinging  on  the  inferior  turbinate  and  acting  as  a 
continual  irritant  to  the  naso-pharynx,  should  be  corrected.  Cases  of 
marked  deviation  associated  with  moderatch'  atrophic  condition  of 
the  mucus  membranes  do  not  necessarily  require  operations.  The 
prime  object  is  to  prevent  acute  post-nasal  trouble  which  might  come 
on  as  a  result  of  exposure,  rather  than  to  attempt  to  obviate  an  in- 
sidious middle  ear  catarrh  which  might  have  come  on  in  later  life. 

The  nares  should  be  most  carefully  examined  for  any  signs  of 
accessory  sinus  disease.  Even  a  suspicion  of  this  condition  should 
lead  to  a  most  careful  and  painstaking  examination  and  reexamina- 
tions, including  properly  taken  X-ray  stereoscopic  photographs. 

CONDITIONS  OF  TONSILS. 

The  diagnosis  of  diseased  tonsils  is  a  difficult  one  and  must  be 
left  largely  to  the  experience  of  the  individual  examiner.  Appli- 
cants are  disinclined  to  admit  a  history  of  sore  throats.  It  must  not 
be  forgotten  that  probably  80  per  cent  of  the  sick  call  on  the  other 
side  is  made  up  of  sore  throats.  Soldiers  who  never  complain  of 
throat  trouble  in  this  country,  when  thej-  are  subjected  to  the  ex- 
posure incidental  to  field  service,  rapidly  develop  inflammatory 
throat  conditions  which  render  them  temporarily  unfit  for  duty. 
One  should  be  cautious  in  declaring  a  tonsil  healthy.  All  throats 
should  be  examined  under  good  illumination;  attempt  to  express 
contents  of  crypts  should  be  made  and  if  questionable  matter  can 
be  squeezed  out  the  tonsils  should  be  removed.  Buried  tonsils  should 
be  removed,  as  should  the  true  hypertrophic  type.  The  experience 
of  this  service  has  been  that  in  spite  of  the  fact  that  all  applicants 
were  originally  examined  by  throat  specialists,  many  when  reex- 
amined showed  chronically  diseased  tonsils.  In  general  it  is  better 
to  err  slightly  on  the  side  of  radicalism  in  regard  to  operation  on  the 
tonsils  for  those  about  to  enter  active  military  service. 

PRESENCE   or   ADENOIDS. 

Adenoid  tissue  is  very  common  in  children  and  increases  in  size 
from  birth  to  the  age  of  six  years  and  then  normally  subsides  about 
the  age  of  puberty.  One  does  not  expect  to  find  much  adenoid  tissue 
in  adults.  Adenoids  do  their  harm  early  in  life,  and  this,  as  far  as 
it  concerns  this  examination,  is  evidenced  by  deformed  jaws,  mis- 
shapen noses,  and  poor  hearing.    Adenoid  tissue  in  the  adult  is  easily 


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Aifi  SERVICE   MEDICiX,.  75 

seen  with  a  post-nasal  mirror,  the  digital  examination  being  unneces- 
sary. 

CONDITION    OF    EUSTACHIAM    TUBES. 

The  condition  of  the  Eustachian  tubes  is  one  of  vital  importance 
to  the  aviator.  Generall}^  speaking,  it  can  be  said  that  if  the  appli- 
cant's drumhead  and  hearing  is  normal,  the  Eustachian  tube  is  prob- 
ably in  good  condtion.  In  addition,  regulations  require  that  the 
patulence  of  the  tube  should  be  demonstrated  by  the  auscultation 
tube  during  inflation  by  means  of  Politzerization  or  catheretization. 
The  former  procedure  is  ample  for  all  practical  purposes.  If  tubal 
troubles  are  of  such  a  nature  as  to  demand  it,  an  examination  should 
be  made  with  some  good  pharyngoscope. 

STATIC   AND   DYNAMIC   TESTS. 

In  the  static  test  the  applicant  is  required  to  stand  in  the  position 
specified  with  his  eyes  closed  for  one  minute.  Too  much  importance 
must  not  be  attached  to  the  fact  that  the  applicant  is  slightly  un- 
steady. They  expect  that  this  and  the  dynamic  test  is  some  sort  of 
a  trick  examination  and  become  very  nervous.  Some  sway  markedly 
and  are  unable  to  walk  in  a  straight  line.  Disqualification  on  these 
tests  should  only  be  made  with  the  greatest  reservation  and  when 
confirmed  by  other  tests,  showing  that  the  applicant  has  marked 
instability  of  his  coordinating  mechanism.  In  the  thousands  of 
applicants  so  far  examined  none  were  rejected  for  these  causes  alone. 
In  the  dynamic  test  if  the  applicant  swerves  more  than  three  feet 
from  the  straight  line,  he  must  be  asked  to  repeat  the  test  until  the 
examiner  is  convinced  that  his  deviation  from  the  line  is  so  abnormal 
as  to  be  a  ciuse  for  rejection. 

TURNING-CHAIK     (eAK    MOTION-SENSING )     TESTS. 

The  motion-perceiving  apparatus  of  the  internal  ear  is  subjected 
to  stimulation  by  motion  of  certain  standard  quantity  and  quality, 
and  the  results  are  observed  according  to  uniform  standard  methods. 
Two  results  are  noted — a  sensory  result,  the  subjective  sensation  of 
motion,  and  a  motor  result,  involuntary  movement  of  the  eyes.  When 
the  subjective  sensation  of  motion  is  in  accord  with  fact,  we  call  it 
normal  sensing  of  motion ;  when  it  is  not  in  accord  with  fact,  we  call 
it  "vertigo."  The  only  difference  between  normal  perception  and 
vertigo  lies  in  the  sensing  of  motion  being  in  accord  with,  or  con- 
trary to,  fact.  The  most  practical  means  of  applying  motion  stimulus 
is  by  the  rotating  chair,  inasmuch  as  the  application  of  motion  in  a 
linear  direction,  for  the  period  of  time  and  in  the  intensity  neces- 
sary to  elicit  certain  standard  responses  to  that  stimulus,  would 
necessitate  apparatus  entirely  too  bulky  to  be  susceptible  of  practical 


^6  AIR  SERVICE  MEDICAL. 

application  under  ordinary  conditions  of  office  examination.  By 
making  use  of  a  rotational-motion  stimulus  instead  of  a  linear-motion 
stimulus,  it  was  possible  to  work  out  a  standard  means  of  applying 
motion  stimulus  in  certain  definite  quality  and  quantity  in  a  manner, 
and  by  means  of  an  apparatus  easily  handled  in  an  office.  For  this 
reason  only,  the  subject  of  the  tests  of  the  vestibular  apparatus  is 
made  to  experience  rotational  vertigo.  An  additional  advantage  in 
using  the  rotating  chair  is  that  it  applies  motion  stimulus  of  a  char- 
acter to  produce  a  more  enduring  stimulation  of  the  end-organs  of 
the  semicircular  canals. 

Motion  in  a  linear  direction  applied  to  a  fluid  contained  in  a  semi- 
circular canal  is  physically  incapable  of  setting  up  a  flow  of  that 
fluid,  just  as  rotational  motion  applied  to  a  fluid  contained  in  a 
straight  canal  can  not  set  up  a  flow. 

Ewald's  experiment  long  ago  determined  that  involuntary  pulling 
of  the  eyes  in  a  certain  definite  direction  and  plane  occurs  during 
the  time  the  fluid  in  a  normal  semicircular  canal  is  made  to  flow  in 
one  direction;  and  during  the  time  this  fluid  is  made  to  flow  in  the 
opposite  direction  involuntary  pulling  of  the  eyes  in  the  opposite 
direction  occurs.  By  applying  rotational  motion,  it  is  possible  to 
reproduce  Ewald's  experiment  in  effect,  as  a  test  of  eye  reactions  to 
vestibular  stimulation;  and  when  the  character  and  intensity  of 
rotational  stimulus  is  standardized,  comparisons  of  the  results  can 
be  made  and  a  normal  eye  reaction  determined.  This  motor  expres- 
sion of  motion  stimulation  is  nystagmus. 

The  normal  man  experiences  a  sensation  of  vertigo  for  between  15 
and  40  seconds  after  being  turned,  according  to  standard  technique. 
Evidence  of  this  subjective  sensation  may  be  had  by  voluntary  or 
involuntary  testimony ;  voluntary  testimony  such  as  "  I'm  turning 
to  the  right,"  "  I'm  still  turning  to  the  right,"  etc.,  during  the  per- 
sistence of  the  subjective  sensation;  involuntary  testimony,  such  as 
the  pointing  test  and  the  falling  test.  Standard  tests  make  use  of 
involuntary  testimony  in  all  cases;  occasionally  this  is  amplified  by 
voluntary  testimony  with  advantage.  In  observing  the  pointing  be- 
fore turning,  a  very  important  element  in  the  test  can  be  injected 
by  implanting  in  the  mind  of  the  applicant  the  definite  idea  that  he 
is  to  attempt  to  determine  the  location  in  space  of  the  observer's 
finger,  solely  by  registering  in  his  memory  the  location  of  it  accord- 
ing to  his  tactile  sense.  This  can  be  augmented  by  having  him  touch 
the  observer's  finger,  in  more  than  one  position ;  as,  for  instance,  di- 
rectly in  front  of  the  right  hand,  come  back  and  touch ;  then  locate 
again  30  degrees  outward  and  come  back  and  touch;  the  same  pro- 
cedure in  front  of  the  left  hand.  This  implants  in  his  mind  the 
fundamental  idea  of  being  able  to  orientate  himself  solely  by  means 
of  information  coming  from  his  tactile  sense.    After  standard  rota- 


.  •»  »     »  : ,  J 


1  »    » > 


»         »     1  >      >    1      '     T 


TESTING  FOR  SPONTANEOUS  NYSTAGMUS  BEFORE  TURNING. 


r<;ij-i 


Popular  Science  Monthly 


CAN  HE  PILOT  A  BATTLI'^I'LAXE. 


To  find  out  if  his  ear  motion-sense  is  good  he  is  whirled  around  in  a  special  chair.  Tlif  object  of  t  ho 
whirling  is  to  displace  the  fluid  in  the  inner  ear,  the  fluid  that  controls  the  oar  motion-sense  and 
tells  whether  he  is  moving  or  not.    The  examiners  then  note  how  longit  takes  him  to  recover  poise. 

76b-2 


'PTJT-     xPuiir'AV'P   FVTVVDS    KI^    RIGHT   ARM   xVXD    TOT^CHKS   THE    EXAMINER'S 
'hIn^D      THEN  HE   RA^SK^^  AND  IS  TOLL  TO   BRING   HIS 

FINGER  BACK  AND  TOUCH  THE  EXAMINER'S  HAND  AGAIN. 


This  is  done  with  the  eyes  closed.    See  fig.  8245  for  result  after  turning. 


76b-3 


AFTER  TURNING  APPLICANT  RAISES  THE  FINGER  IN  AIR  AND  ATTEMPTS  TO  TOUCH 

EXAMINER'S  FINGER. 

76b-4 


FT^VTVP  TiFFK  TrRXED  TEN  TIMES  IN  TEN  SECONDS  TO  THE  RIGHT  AND   BEl'^" 
STOPPED    THE   ENDOLY^VnCONTm  TO   FLOW  TO   THE   RIGHT  WHICH 

MAKES  IT  APPEAR  THAT  HE  IS  TURNING  TO  THE  LEFT. 

This  dvcs  him  false  orientation  wliich  causes  him  to  past-point  to  the  riglU.,  which  he  cmitinues  to 

do  so  long  as  the  endolymph  flows. 

7()b— 5 


PUTTING  HIM  THROUGH  THE  FAULIXG  TEST. 

The  applicant  is  placed  in  a  chair  with  his  head  forward  approximately  ninety  degrees  to  bring  the 
vertical  canals  of  the  inner  ear  in  the  horizontal  plane.  After  having  been  turned  five  times  in 
ten  seconds  to  the  left,  for  example,  he  feels  that  he  is  falhng  to  the  right  when  he  sits  up  with 
his  eyes  closed. 

77b-l 


PUTTING  HIM  TIIKOUGH  THE  FALLING  TEST. 


After  having  lu'ccn  lurticd  five  times  in  (en  seconds  (o  llic  left,  with  the  eyes  closed,  whicli  causes  the 
llowing  of  tlie  endolynii)h  in  the  direction  of  the  turning,  the  applicant,  upon  sitting  up,  feels  that 
he  is  falling  to  the  right,  because  of  this  endolymph  movement.  He  tries  to  overcome  this  and 
actually  falls  to  the  left. 

77b-2 


AlE  SERVICE   MEDICAL.  77 

tion  of  the  right,  for  example,  normal  man  experiences  certain  very 
definite  vertigo — a  subjective  sensation  of  turning  to  the  left  in  the 
same  plane  as  the  rotation,  for  a  normal  period  of  time.  If  the 
pointing  test  is  carried  out  during  this  period  of  vertigo,  instead  of 
succeeding  in  pointing  accurately  to  the  testing  finger,  he  executes 
the  pointing  in  accordance  with  his  subjective  sensation  of  motion. 
Feeling  that  he  is  turning  definitely  away  from  the  testing  finger,  to 
the  left,  he  reaches  for  it  to  the  right.  This  is  normal  past-pointing. 
The  insulation  of  the  applicant  during  this  test  should  be  as  perfect 
as  possible.  A  black  domino  mask  should  be  used,  absolute  quiet 
should  be  maintained,  olfactory  impressions  should  be  shunted  out, 
and  he  should  be  left  as  solely  as  possible  dependent  upon  the  infor- 
mation brought  to  him  along  the  vestibular  tract  alone.  The  appli- 
cant should  be  definitely  instructed  before  turning  that  he  should 
not  expect  a  verbal  order  to  touch  the  observer's  finger,  raise  his  hand 
and  come  back,  and  attempt  to  find  it  after  the  turning;  he  should 
be  practiced  before  turning,  in  executing  his  touch,  raising  his  hand, 
and  coming  back  to  find  the  finger  upon  receipt  of  the  signal  from 
the  observer's  finger  as  it  comes  into  the  position  which  it  maintains 
during  the  test — the  observer  bringing  up  his  finger  into  position 
so  as  to  tap  the  applicant's  finger  as  a  signal  for  him  to  execute  his 
pointing,  without  verbal  command.  It  is  very  important  for  the 
applicant's  finger  to  find  a  finger  of  the  observer  when  he  comes 
down  in  search  of  the  finger  which  is  testing  him.  Otherwise,  there 
is  injected  into  his  mind  a  disconcerting  element  of  dissatisfaction 
in  having  failed  to  find  the  finger  for  which  he  was  searching.  For 
this  purpose  the  index  finger  of  the  observer's  left  hand  can  be  held 
in  readiness  to  furnish  the  touch  necessary  to  shunt  out  this  sense  of 
failure.  In  observing  the  past-pointing  after  rotation,  the  observer's 
right  index  finger  should  be  definitely  fixed  against  the  observer's 
hip,  so  that  visual  attention  to  it  on  the  part  of  the  observer  can  be 
dispensed  with,  the  hip-rest  insuring  its  remaining  definitely  where 
it  was  when  the  applicant  first  touched  it  in  making  the  pointing 
test.  The  observer's  eyes  can  be  free  to  watch  the  applicant's  finger 
at  the  top  of  the  swing.  Past-pointing  at  the  top  of  the  swing  is 
just  as  definitely  normal  past-pointing  as  at  the  completion  of  return 
to  touch.  Many  cases  compensate  after  evincing  a  normal  tendency, 
let  us  say,  to  past-point  outward  with  the  right  hand  when  they 
should  do  so,  and  subsequently  execute  a  compensatory  touch  or 
inward  pointing  at  the  bottom  of  the  return.  In  such  cases  the  point- 
ing should  be  registered  as  that  executed  at  the  top  of  the  swing, 
which  is  the  primary  and  clean  response  before  it  has  been  altered 
by  the  subconscious  or  conscious  compensation  effected  by  other 
mental  processes.  Visual  attention  on  the  part  of  the  observer  to 
the  applicant's  hand  at  the  beginning  of  his  downward  pointing  is 


78  ATE  SEEVICE  MEDICAL. 

of  enormous  importance  and  it  should  be  very  carefully  observed  as 
part  of  the  standard  technique. 

The  falling  test  is  similar.  A  normal  man,  on  attempting  to  sit 
upright  after  leaning  forward  during  right  rotation,  feels  that  he  is 
turning  to  the  left,  for  instance,  and  so  gives  involuntary  expression 
to  this  sensation  by  falling  to  the  right  on  attempting  to  assume  an 
erect  sitting  posture. 

These  tests  can  be  completed  in  less  than  five  minutes.  Inci- 
dentally, these  tests  are  in  no  sense  severe  and  are  in  fact  seldom 
regarded  even  as  unpleasant.  Occasionally  nausea  occurs  after  these 
turnings;  it  is  then  merely  necessary  to  stop  the  examination  for 
the  time  being  and  complete  the  remainder  of  the  tests  after  an 
interval  of  half  an  hour.  There  is  no  need  whatever  to  make  these 
tests  in  any  way  distressing  to  the  applicant. 

With  respect  to  the  internal  ear  motion-sensing  apparatus,  its 
nerve-paths  and  brain  connections,  these  turning-tests  quickly  sepa- 
rate the  obviously  fit  from  the  unfit.  The  majority  of  the  applicants 
show  normal  responses ;  no  further  testing  is  required  and  they  there- 
fore qualify  and  are  accepted.  Some  applicants  show  such  markedly 
subnormal  responses  that  they  are  immediately  disqualified  and  re- 
jected. A  limited  number  give  what  might  be  termed  "  border-line  " 
responses;  the  question  then  arises.  Has  this  particular  applicant 
sufficient  ear  motion-perceiving  sense  to  become  an  aviator?  It  is 
here  that  the  caloric  test  is  useful.  The  turning  has  tested  both  the 
right  and  left  ears  simultaneously.  The  caloric  method  enables  us 
to  test  each  ear  separately.  Water  at  68°  F.  is  allowed  to  run  into 
the  external  auditory  canal  from  a  height  of  about  3  feet  through  a 
stop-nozzle,  with  the  head  tilted  30°  forward,  until  the  eyes  are  seen 
to  jerk  or  the  individual  becomes  dizzy.  The  length  of  time  from 
the  beginning  of  the  douching  untU  the  jerking  of  the  eyes  becomes 
apparent,  or  until  the  applicant  says  he  is  dizzy,  is  accurately  meas- 
ured by  a  stop-watch.  The  type  of  nystagmus  is  then  noted.  With 
head  in  upright  position,  it  should  be  rotary  and  the  direction  of  the 
jerk  should  be  to  the  side  opposite  the  ear  douched.  The  length  of 
the  douching  show^n  by  the  stop-watch  in  the  normal  is  40  seconds. 
The  eyes  are  then  closed  and  the  past-pointing  is  taken.  The  head 
is  then  immediately  inclined  backward  60°  from  the  perpendicular 
(or  90°  from  the  original  position).  There  should  then  appear  a 
horizontal  nystagmus  to  the  side  opposite  to  the  ear  douched.  The 
eyes  are  then  closed  and  the  past-pointing  is  taken  with  the  head  in 
this  position.  The  left  ear  is  then  douched  and  the  same  procedure 
carried  out.  If  the  caloric  test  applied  to  one  of  these  "  border-line  " 
cases  shows  only  a  slight  impairment  of  the  responses  from  each  ear, 
the  applicant  is  qualified.  If  instead  of  40  seconds  of  douching 
there  was  required  not  moi-e  than  90  seconds  of  douching  to  elicit 


79b-l 


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79b-3 


SHOWING  TYPE  OF  YOUNG  PHYSICAL  MANHOOD  WHO  CAME  UP  FOR  EXAMINATION 
79b-4 


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AIE  SERVICE   MEDICAL.  r    79 

normal  responses,  the  applicant  is  not  rejected.  Care  should  be 
taken  to  be  certain  that  the  cold  water  is  reaching  the  drumhead 
during  this  caloric  test,  as  wax  or  other  obstruction  in  the  external 
canal  would  interfere  with  the  responses  in  a  perfectly  normal 
individual. 

After  carefully  considering  the  foregoing,  the  neurologist  and  the 
general  diagnostician  can  not  fail  to  be  struck  with  the  comprehen- 
sive character  of  these  vestibular  tests.  Frequently  they  are  looked 
upon  as  Ear  tests  only.  Six  months  ago  one  of  the  greatest  otologists 
of  Europe,  in  discussing  these  tests,  raised  the  question  as  to  the 
necessity  or  advisability  of  including  in  aviation  examinations  the 
past-pointing  and  falling  tests,  his  contention  being  that,  in  testing 
nystagmus  only,  one  secures  definite  evidence  of  the  functional  state 
of  the  semicircular  canal  end-organs  of  the  internal  ear.  When  his 
attention  was  drawn  to  the  fact  that,  in  testing  the  past-pointing  and 
falling  in  addition  to  the  nystagmus,  one  establishes  definitely  the 
functional  intactness-  (1)  of  the  various  afferent  paths  and  the  in- 
tracranial structures  through  which  they  pass,  (2)  of  the  cerebral 
cortical  centers  and  their  transcortical  association  tracts,  (3)  the 
afferent  cerebral  paths  and  the  nuclei  through  which  they  pass,  (4) 
the  cerebellar  nuclei  and  correlation  paths  to  and  from  cerebellar 
cortical  centers,  (5)  various  portions  of  the  Pons  and  Medulla  Ob- 
longata, his  attitude  was  completely  changed  and  he  became  a  firm 
advocate  of  the  complete  testing  of  nystagmus,  past -pointing  and 
failing  as  a  routine  procedure. 

It  can  not  be  emphasized  too  strongly  that  the  vestibular  tests  are 
net  merely  tests  of  the  internal  ears.  To  be  sure,  these  tests  do  deter- 
mine the  functional  integrity  of  the  internal  ear;  but  in  addition 
they  determine  the  functional  integrity  of  a  large  portion  of  the 
Central  Nervous  System. 

HEIGHT  AND  WEIGHT. 

The  standard  limits  of  height  and  weight  are:  Minimum  height, 
60  inches ;  maximum  height,  no  limit.  Minimum  weight,  110  pounds ; 
maximum  weight,  180  pounds,  with  10  pounds  leeway. 

CHEST  MEASUREMENT. 

It  has  transpired  that  a  low  vital  capacity  (by  which  is  meant 
the  amount  of  air  that  can  be  expelled  from  the  lungs  after  full  in- 
spiration) is  undesirable  in  aviators.  This  may  be  roughly  estimated 
by  an  expansion  of  not  less  than  3  inches  in  an  individual  of 
average  size.  The  judgment  of  the  examiner  should  be  applied  in 
seeing  that  the  expiration  and  inspiration  measurements  are  com- 
mensurate with  the  size  of  the  applicant. 

89118—19 6 


80  •  AJE  SEBVICE  MEDICAL. 

BESPIRATORY  SYSTEM. 

In  examining  the  chest,  attention  must  be  paid,  in  connection  with 
other  signs,  to  any  indications  of  an  incipient  tuberculosis.  It  is  al- 
ways safer  if  such  a  condition  is  suspected  to  order  an  X-ray  exami- 
nation. On  account  of  various  disputes  which  have  arisen  over  this 
point,  many  units  have  found  it  extremely  valuable  to  retain  these 
plates  for  their  permanent  record. 

BONE   AND    JOINTS. 

In  making  this  examination  it  is  well  to  put  the  applicant  through 
several  of  the  Army  setting-up  exercises.  The  applicant  is  first  in- 
structed to  touch  his  fingers  to  the  floor  without  bending  his  knees. 
He  must  next  tread  water,  that  is,  he  is  instructed  to  bring  each 
knee  alternately  up  to  his  chest  and  back  again.  He  is  next  instructed 
to  spring  into  the  air,  striking  his  buttocks  with  his  heels ;  he  is  made 
to  squat,  keeping  his  knees  apart.  Flexion  extension  and  rotation 
of  upper  extremities  complete  the  necessary  information  as  to  bones 
and  joints.  It  is  safe  to  pass  as  nondisqualifying,  second  degree  of 
flat  foot  of  rather  extreme  proportions,  providing  there  is  absence 
of  symptoms  of  incapacitation. 

SKIN. 

Such  skin  diseases  as  general  acne  vulgaris  and  psoriasis  of  exten- 
sive distribution  should  be  regarded  as  disqualifying.  Some  cases  may 
be  cleared  up  by  treatment,  and,  as  in  all  similar  disqualifications, 
the  elimination  of  the  condition  should  permit  the  applicant  qualify- 
ing for  service.  The  underlying  reason  for  disqualification  of  this 
character  is  that  barrack-mates  and  tent-mates  of  the  victims  of  such 
skin  diseases  are  prone  to  regard  them  as  of  a  contagious  and  danger- 
ous nature,  and  the  admission  of  such  into  the  service  is  bound  to 
engender  widespread  disquiet  and  discontent  on  the  part  of  others. 

NERVOUS    SYSTEM. 

The  nervous  system  has  been  subjected  to  a  rather  extensive 
scrutiny  by  the  examinations  entailed  by  questions  Nos.  2,  3,  4,  8, 
9,  10,  11,  12,  14  (c),  19  and  above  all,  20.  Additional  observations 
should  be  made  concerning  tremor  (which  may  be  the  cue  to  more 
extensive  examinations  of  the  thyroid  and  its  associated  endocrine 
system),  various  motor  coordinations  with  closed  eyes,  such  as  bring- 
ing the  tips  of  the  index  fingers  together  with  arms  outspread, 
bringing  the  tips  of  the  index  fingers  into  delicate  touch  with  the  tip 
of  the  nose,  etc. ;  cutaneous  sensibilities  and  deep  reflexes. 


EXAMINING  THE  BONES  AND  JOINTS  AND  GENERAL  MUSCULATURE. 
SOb-l 


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AIR  SERVICE  MEDICAL.  81 

VASCULAR   SrSTEM. 

Concerning  the  vascular  system,  the  dissertation  contained  in  the 
general  instructions  is  very  full  and  constitutes  an  almost  classical 
guide  to  such  examinations.  The  systolic  blood  pressure  taken  by 
the  mercury  column,  or  by  an  aneroid  instrument  carefully  cor- 
rected as  to  reliability,  should  not  exceed  145  mm.;  the  diastolic 
should  show  commensurate  pulse  pressure;  the  remainder  when 
diastolic  is  subtracted  from  systolic  should  be,  roughly,  one-half  the 
diastolic  figure.  For  instance;  systolic  120,  diastolic,  80;  remainder, 
40,  which  is  one-half  of  80.  Systolic  murmurs  in  the  presence  of 
definitely  (1)  good  muscle  sound,  (2)  good  valve  closure  sound, 
(3)  absence  of  stenotic  sounds,  (4)  apex  beat  in  mid-clavicular  line, 
(5)  normal  percussion  outlines,  (6)  absence  of  history  of  an  etiologic 
character,  (7)  absence  of  history  of  cardiac  character,  may  be  safely 
construed  as  nondisqualifying;  especially  may  this  be  so  construed 
if  marked  alteration  in  the  character  of  the  murmur  ensues  upon 
change  of  posture  or  exercise.  Moderate  varicosities  without  any 
symtoms  should  not  be  regarded  as  disqualifying. 

DIGESTIVE    SYSTEM. 

Examination  of  the  teeth  must  not  be  neglected.  It  must  never  be 
forgotten  that  crowned  teeth,  pyorrhea,  and  alveolar  infections  may 
be  the  sources  of  much  toxemia.  Special  attention  should  be  given 
to  this  matter  and  if  there  is  any  doubt  in  the  mind  of  the  examiner 
as  to  the  condition  of  the  candidate's  teeth,  his  mouth  should  be  put  in 
good  shape  before  final  acceptance.  In  addition  to  the  findings  con- 
cerning the  digestive  system,  see  that  the  imprint  indicating  missing 
teeth  appears  at  the  right  side  of  line  29. 

/ 

HERNIA. 

No  hernia  or  any  dangerous  condition  of  weak  scars  should  be  ac- 
cepted. Successful  operation  for  hernia  permits  applicant  qualify- 
ing, however. 

GENITO-URINARY  SYSTEM. 

No  focal  infection  or  chronic  disease  of  the  genito-urinary  tract 
and  no  venereal  disease  should  be  accepted. 

URINALYSIS. 

A  great  many  applicants  show  transitory  albuminuria  of  a  non- 
disqualifying  character,  so-called  orthostatic  or  postural  albumi- 
nuria. It  is  necessary  to  determine  that  an  albuminuria  is  transitory 
and  that  it  is  definitely  not  renal  in  origin,  as  would  be  shown  by 


82  AIB  BEEVICE  MEDICAL. 

the  absence  of  casts,  cylindroids,  renal  epithelium  or  other  renal 
elements.  In  this  connection  it  is  interesting  to  note  that  at  one  of 
the  examining  units  for  a  period  of  nine  days  every  applicant  showed 
albuminuria.  The  cause  of  this  was  found  by  the  members  of  the 
unit  to  be  the  taking  of  urine  specimen  at  the  end  of  the  examina- 
tion. It  is  absolutely  necessary  to  adhere  to  the  routine,  taking  the 
urine  samples  at  the  beginning  of  all  examinations.  If  albumin  has 
been  found  in  the  urine,  which  may  be  of  a  temporary  nature,  the 
examination  blank  must  not  be  turned  in  until  the  three  additional 
examinations  are  made  on  three  successive  days.  The  results  of  such 
examinations  should  be  typed  in  the  lower  left-hand  corner  of  the 
last  page  just  under  the  numerals  "  33  "  and  if  at  the  end  of  the  third 
day  the  urine  is  found  free  from  albumin,  the  applicant  is  marked 
as  physically  qualified  and  the  examination  blank  turned  in. 

FINAL  QUESTION — IS  THE  APPLICANT  PHYSICALLY  QUALIFIED  ? 

After  the  examinations  have  all  been  made  the  oflBcer  in  charge  of 
the  unit  must  answer  "  Yes  "  or  "  No  "  to  the  final  question.  If  the 
applicant's  examination  has  been  satisfactory  in  all  respects,  the  word 
"  Yes  "  is  placed  on  the  first  line  followed  by  his  signature.  If  one 
or  more  actual  disqualifications  have  been  found,  the  word  "  No  "  is 
placed,  followed  by  the  numbers  indicating  the  examination  on  which 
the  applicant  was  disqualified. 


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82b-2 


CHAPTER  V. 

STATISTICAL  REPORT  OF  RESULTS  OF  THE  EXAMINA- 
TIONS MADE  BY  THE  67  PHYSICAL  EXAMINING  UNITS. 


STATISTICAL  REPORT  OF  THE  PHrSICAL,  EXAMINATION  OF  APPLICANTS  FOR 

COMMISSION    IN    THE   AIR    SERVICE. 

A  careful  tabulation  has  been  made  of  the  results  of  the  phj^sical 
examination  of  all  men  who  applied  for  detail  as  cadet  fliers.  Indi- 
vidual units,  in  many  cases,  sent  in  comprehensive  reports,  but  the 
methods  employed  and  the  results  obtained  were  so  varied  that  it 
was  found  inexpedient  to  consolidate  their  findings.  The  following 
tables  were  obtained  through  access  to  the  original  examination 
papers  after  they  had  been  forwarded  from  the  67  units  to  their  final 
haven  in  Washington.  From  these  papers  the  required  data  was  ob- 
tained. That  in  turn  was  punched  on  cards  which  were  assembled 
and  tabulated  according  to  the  method  employed  at  present  for  get- 
ting statistical  returns  involving  large  numbers. 

The  accuracy  of  the  findings  of  many  individual  units  has  been 
established  by  their  close  resemblance  to  the  returns  of  the  work  when 
done  as  a  whole. 

The  outstanding  point  of  interest  is  the  fact  that  of  those  who  came 
up  for  physical  examination,  70.7  per  cent  qualified,  and  29.3  per 
cent  were  rejected. 

Separating  the  causes  of  disqualification  into  nine  groups,  the 
following  rates,  based  on  the  total  number  examined,  are  obtained: 

Per  cent. 

1.  Eye 5.  9 

2.  Ear 1.  2 

3.  Nose  and  throat .8 

4.  Equilibrium 2.  0 

5.  Vascular  system 1.  5 

Q.  Urinalysis .  4 

7.  Other  and  general  subnormalities 1.9 

8.  Disqualified  on  two  tests 7.  0 

9.  Disqualified  on  three  or  more  tests 8.  6 

Total • 29.3 

It  is  interesting  to  note  that  for  any  one  cause  of  rejection  the  fail- 
ure to  meet  the  eye  requirements  easily  leads,  being  5.9  per  cent;  7 
per  cent  were  rejected  for  failure  to  meet  two  tests  and  8.6  per  cent  foi 
inability  to  meet  three.    Although  the  present  compilation  does  not 

83 


84  AIB  SERVICE  MEDICAL. 

show  it,  from  conclusions  drawn  from  the  statistics  of  certain  units, 
it  can  easily  be  taken  for  granted  that  visual  defects  were  present  in 
at  least  half  of  the  cases  where  men  failed  on  two  or  more  comits. 
In  other  words,  it  is  safe  to  assume  that  practically  50  per  cent  of 
those  rejected  failed  to  meet  the  eye  requirements. 

In  giving  the  results  of  the  eye  tests,  it  will  be  noticed  that  the 
highest  rate  of  failure  is  accorded  to  visual  acuity — 3.3  per  cent,  or 
more  than  one-half  of  the  total  number  rejected  on  this  particular 
count. 

Next  in  order  of  importance  come  color  vision,  muscle  balance, 
and  stereoscopic  vision,  their  combined  rates,  2.2  per  cent,  accounting 
in  a  large  degree  for  the  balance  of  those  who  failed  in  the  eye  tests. 
It  will  be  observed  that  the  percentages  of  failure  through  other 
visual  defects  are  very  small,  indeed,  averaging  about  four  out  of 
every  thousand  examined. 

The  following  table  gives  the  rates  of  failure  in  the  eye  tests  classi- 
fied according  to  causes : 

Per  cent. 

History  of  eye  trouble 0.  03 

Stereoscopic    vision .  5 

Ocular  movements , .  04 

Pupillary    reactions .  01 

Intraocular   tension .  003 

Visible  lesion  of  eyes _ .  03 

Ocular  nystagmus .02 

Field  of  vision .  003 

Color  vision 1. 

Muscle  balance .  7 

Visual  acuity 3.  3 

Ophthalmoscopic   findings .  3 

Total 5.  936 

The  greater  part  of  the  rejections  of  those  who  failed  in  the  ear 
tests  was  due  to  defects  of  the  external  auditory  canal  and  hearing, 
being  1  per  cent  out  of  a  total  of  1.2  per  cent,  or,  one  out  of  every 
100  examined. 

The  specific  causes  of  disqualification  with  rates  are  as  follows: 

Per  cent. 

History  of  ear  trouble 0. 1 

Appearance  of  extern;il  auditory  canal  and  hearing 1. 

Appearance  of  membruni  tympani , .  1 

Total r 1-2 

Eight-tenths  per  cent  or  8  men  out  of  every  1,000  men  examined 
were  disqualified  on  account  of  naso-pharynx  defects,  0.4  per  cent  of 
which  was  due  to  condition  of  the  nares,  0.4  per  cent  due  to  condi- 
tion of  tonsils,  other  naso-pharynx  causes  being  entirely  negligible. 

The  equilibrium  tests  proper,  exclusive  of  the  static  and  dynamic 
tests,  are  cause  for  practically  all  of  the  rejections  in  this  particular 


AIB  SERVICE  MEDICAL.  85 

field,  being  2  per  cent  out  of  a  total  of  2.04  per  cent,  or  2  out  of  every 
100  men  examined.  The  average  duration  of  nystagmus  of  the  entire 
number  of  men  examined  was,  after  turning  to  the  right,  23.5  sec- 
onds; after  turning  to  the  left,  23.2  seconds.  In  those  who  qualified, 
the  nystagmus  after  turning  to  the  right  was  23  seconds,  after  turn- 
ing to  the  left,  23.1  seconds. 

It  will  be  observed  that  these  findings  are  almost  identical  with  the 
average  duration  of  nystagmus  of  the  total  number  examined.  In 
getting  an  average  on  nystagmus  duration  the  result  is  neutralized 
by  a  combination  of  hypersensitives  and  subnormalities ;  in  other 
words,  some  cases  revealed  a  high  degree  of  nystagmus,  while  others 
fell  far  below  normal.  It  was  accordingly  found  expedient  to  sepa- 
rate the  duration  of  nystagmus  into  two  groups,  that  which  was  less 
than  16  seconds  and  that  which  was  over  36  seconds. 

The  average  duration  of  nystagmus  of  those  who  showed  less  than 
16  seconds  after  turning  to  the  right  was  12.4  seconds,  after  turning 
to  the  left,  12.5  seconds. 

The  average  duration  of  nystagmus  of  those  who  showed  more 
than  36  seconds  after  turning  to  the  right  was  50.2  seconds,  and  after 
turning  to  the  left,  48  seconds. 

The  average  number  of  past-pointings  for  the  total  number  ex- 
amined is  as  follows: 

Times. 

After  turning  to  right  with  right  arm 3.  8 

After  turning  to  right  with  left  arm 3.  7 

After  turning  to  left  with  right  arm 3.  8 

After  turning  to  left  with  left  arm 3.  7 

The  average  number  of  past-pointings  for  those  who  qualified  was : 

Times. 

Aft*  turning  to  right  with  right  arm 3.  9 

After  turning  to  right  with  left  arm 3.  8 

After  turning  to  left  with  right  arm 3.  9 

After  turning  to  left  with  left  arm 3.  8 

In  failure  to  qualify  in  the  vascular  system  requirements,  heart 
defects  lead,  being  seven  times  as  great  as  respirak)ry  causes.  This 
in  itself  signifies  but  little,  for  all  vascular  system  defects  amount 
to  but  1.5  per  cent,  or  15  out  of  every  1,000  men  examined.  The  fol- 
lowing table  gives  the  rates : 

Per  cent 

Blood   pressure 0.  2 

Heart .8 

Respiratory   system .  1 

Other   subnormalities .  4 

Total 1.5 

In  the  general  physical  requirements,  the  percentage  of  those  who 
were  rejected  is  0.7  per  cent,  or  7  out  of  every  1,000  men  examined. 
This  rate  is  included  in  the  nine  main  classifications  under,  "  Other 


86 


AIB  SEKVICE  MEDICAL. 


and    general    subnormalities."     Separating    the    general    physical 
causes  into  groups,  the  following  rates  are  obtained : 

Per  cent. 
Over  or  under  age 0.  04 

Bones  and  joints ,  2 

Condition  of  sliin .04 

Condition  of  nervous  system ,  08 

Digestive  system .  07 

Hernia .  i 

Genito-urinary .  2 


Total 


73 


Of  those  who  qualified,  the  following  were  the  percentages  at 


each  age: 
19 

Per  cent. 
0. 3 

30 

20 

3 

31 

21  _  _   _  __ 

_  -  5 

3? 

22 

7.8 

33 

23 

8.5 

34 

24-  _ 

8 

35 

25 

7.2 

36 

26 

6.2 

37 

27 

-  _  4. 3 

38 

28  — 

-  _   3.7 

39 

29 

2.8 

40 

Per  cent. 
__  2.2 
-_  1.3 


.  i 
.3 

2 

.1 
.1 

.04 
.1 
.02 
.01 


Per  cent. 

41 0.01 

42 .  01 

43 .  01 

44 .02 

45 .  0 

46 .  003 

47 .01 

48 - .01 

No  age  given 8.  8 


Total 70.  7 


From  a  combination  of  the  rates  from  the  ages  of  21  to  26,  it  will 
be  observed  that  43  per  cent,  or  nearly  one-half  of  the  number  of 
men  accepted,  qualified  at  these  ages,  the  rate  gradually  lessening 
until  there  are  isolated  cases  of  men  being  admitted  for  some  special 
qualification  at  an  age  beyond  the  limit  prescribed  by  law.  The 
highest  rate  at  any  given  age  is  8.5  per  cent  for  23  years,  or  in  other 
words,  over  8  out  of  every  100  men  who  qualified  were  of  this  age,-  the 
ages  of  22  and  24  furnishing  practically  the  same  quota. 

Of  those  disqualified  on  one  test,  the  percentages  for  each  age  are 
as  follows : 

Per  cent. 


18. 

19. 

20. 

21. 

22. 

23. 

24 

25 

26. 

27. 

28. 

29. 

30 

31 

32 


Per  cent. 

._  e 

.-  .08 

-  .7 
_  1 

._  1.6 
._  1.7 
._  1.5 
._  1.4 
.-  1,3 
._  1 

-  .8 

-  .7 

-  .6 

-  .3 
._  .2 


33 

34 

35 

36 

37 

38. 

39. 

40. 

41. 

42 

43 

44 

45 

46. 

47. 


Owl 

.04 

.03 

.01 

.003 

.02 

.01 


0 


0 


01 

003 

003 

01 

003 

003 


4S 

Per  cent 
0 

49 

0 

50 

0 

51 

_  0 

5? 

__  0 

53 

_  _  0 

54 

_  0 

55 

__  0 

56 

__  0 

57 

__  0 

58 

0 

No 

age  given__ 
Total 

.7 

13.  8 

AIB  SEBVIOE  MEDICAL. 


87 


Of  those  disqualified  on  two  or  more  tests  the  rates  for  each  age  are 
as  follows: 


Per  cent. 
18 0.003 


19. 
20. 
21. 
22. 
23. 
24. 
25. 
26. 
27. 
28. 
29. 
30. 
31. 
32. 


1 
8 
2 
9 

8 


1. 

1 

2 

1. 

1.7 

1.4 

1.1 

1 
.6 
.6 
.3 
.2 


33. 

34. 

35. 

3«. 

37 

38. 

39 

40. 

41. 

42. 

43 

44. 

45. 

46. 

47. 


Per  cent. 

._  .07 

-  .06 
._  .04 

-  .02 
._  ,01 
__  .02 
__  .01 
__  .01 
._  .003 
__  -003 
__  .003 
__  .003 


0 


003 


0 


Per  cent. 

48 0 

49 0 


50. 

51. 

52. 

53. 

54. 

55 

56. 

57. 

58 


0 
0 
0 
0 
0 

0 
0 


003 


.003 


No  age  given .  5 


Total 15. 5 


Reports  of  the  Physical  Examining  Units  at  San  Antonio,  Tex., 
and  Washington,  D.  C,  are  attached. 

Striking  similarity  in  statistical  findings  of  the  entire  series  is 
evident  on  careful  perusal  of  the  details.  It  is  not  necessary  to  ap- 
pend further  detailed  reports  from  other  Examining  Units,  as  these 
two  furnish  sufficient  data  to  constitute  typical  examples. 


EEPOBT    OF    THE    PHYSICAL    EXAMINING    UNIT    AT    SAN    ANTONIO,    TEX. 

1.  From  August  17,  1917,  to  March  12,  1918,  inclusive: 

Total  number  of  applicants  examined 3,  326 

Total  number  of  applicants  failed 894 

Total  number  of  applications  on  file 68 

less      962 

Total  number  of  applicants  accepted 2,364 

Note. — Do  not  try  to  strike  a  percentage  balance  with  these  figures.  Many 
of  those  on  file  have  passed,  but  we  have  not  forwarded  the  papers  on  account 
of  orders  to  stop  examining  after  February  9,  1918. 

2.  For  purposes  of  statistics  our  records  are  available  from  October  1,  1917, 
to  March  12,  1918,  as  follows : 

Accepted : 

Aviators   1, 162 

Aerial  observers  63 

Balloonists    77 

Nonfliers    587 

Rejected : 

Aviators   , 650 

Aerial  observers  ■. 38 

Balloonists    26 

Nonfliers    66 


88  AIB  SERVICE  MEDICAL. 

Percentage : 

Per  cent. 

Aviators  failed  to  pass 36 

Aerial  observers  failed  to  pass 38 

Balloonists  failed  to  pass 25 

Nonfliers  failed  to  pass 10 

3.  Equilibrium  record : 

Total  number  of  men  turned  in  chair 2,  537 

Total  number  of  men  given  caloric  only 10 

Average  duration  of  nystagmus  for  above  2,537  cases  was : 

Right  turn Nystagmus  to  left  duration  22.7  plus  seconds. 

Left  turn Nystagmus  to  right  duration  23  seconds. 

Comparison  of  results  before  and  after  the  use  of  mydriatic. 

Average  duration  of  Nystagmus  taken  before  drops  were  used  in  eyes   (2,123 
men)  : 

Right    turn 22.  7plusseconda 

Left  turn 23.  3  plus  seconds. 

Average  duration  of  Nystagmus  taken  after  a  mydriatic  was  used  in  eyes  (414 
men)  : 

Right    turn 21.  7  plus  secionds. 

Left  turn 22. 1  plus  seconds. 

The  above  shows  practically  no  change  after  the  use  of  a  mydriatic. 
X  Comparison  of  the  findings  by  different  examiners. 

Average  duration  first  100  cases : 

Right  turn 21.  7  plus  seconds. 

Left  turn 23.  3  seconds. 

Average  duration  of  last  100  cases  before  we  began  to  use  a  mydriatic  first : 

Right  turn , 21.  8  plus  seconds. 

Left  turn 23. 1  plus  seconds. 

Average  duration  of  last  100  cases  examined  (mydriatic  used)  : 

Right  turn . 21.  8  plus  seconds. 

Left  turn 22.  9  plus  seconds. 

4.  Of  the  total  of  2,547  men  examined  by  balance  test  151  failed  to  pass  for 
aviators,  which  makes  a  percentage  of  failures  5.9  per  cent. 

Quite  a  few  of  those  included  as  not  passed  for  aviation  in  the  above  para- 
graph were  accepted  as  balloonists. 

EEPOET   OF   THE   PHYSICAL  EXAMINING   UNIT   AT    WASHINGTON,    D.    C. 

The  Washington  unit  has  examined  to  date  (July  5,  1918)  approximately 
3,000  applicants  for  the  Aviation  Section,  Signal  Corps.  Careful  statistics  have 
been  compiled  of  the  results  of  these  physical  examinations.  We  submit  here- 
with a  consecutive  1,000  of  this  number.  The  findings  should  prove  a  reliable 
base  for  estimates  on  greater  numbers.  Seven  hundred  and  sixty-fire,  or  76.5 
per  cent,  were  qualified,  and  235,  or  23.5  per  cent,  were  disqualified. 

Table  2  gives  in  detail  the  results  of  the  physical  examinations  of  the  1,000 
men  consecutively  examined. 

An  applicant  is  often  disqualified  on  more  than  one  count,  but  for  the  pur- 
poses of  classification  the  causes  of  rejection  have  been  separated  into  three 
groups:  (1)  The  eye,  (2)  ear  and  equilibrium,  and  (3)  physical,  the  rejections 
being  classified  according  to  the  main  cau.ses  of  rejection,  with  various  sub- 
divisions, which  are  combined  often  with  counts  of  lesser  importance. 


ATB  SERVICE  MEDICAL. 


89 


Table  II. — SJiowing  the  results  of  the  physical  examination  for  aviation  of  a 
consecutive  1,000  men  at  the  examination  unit,  Washington,  D.  C. 

ACCEPTED. 


Causes. 

Number. 

Rate. 

Total. 

Normal. 

Defect- 
ive. 

Total. 

Normal. 

Defect- 
ive. 

Total 

765 

76.5 

Aee 

18,356 
765 
765 

765 
765 
765 
368 
195 

24 
100 
100 

100 

100 

100 
.5 
.3 

20/18 
20/18 

10.9 
10.8 

100 
100 

100 
100 
100 
100 

100 
100 

29.6 
29.6 

20 
20 

100 
100 

100 
100 
100 
100 

26.2 
25.8 

100 
100 

2.7 
2.7 

2.8 
2.7 

100 
100 
66.4 
140.6 

31.8 

36 
100 
100 

84.2 
127.3 

83.6 
100 
100 
100 
100 
100 
100 
1,017 

Stereoscopic 

757 
762 

765 
764 
764 

8 
»3 

90.0 
99.6 

100 
99.9 
98.6 

1  0 

Color  vi'^ion 

.4 

Muscle  balance: 

Hyperphoria 

Exophoria 

1 
11 

I 

Esophoria 

1    4 

Adc  action 

A  bduction 

Visual  acuity: 

Ri?ht 

Left 

Near  point: 

Right 

8,329.5 
8,273 

765 
765 

765 
765 
765 
765 

765 
766 

22,669 
22,642 

15,282 
15,278 

765 
765 

765 
765 
765 
766 

20,049 
19,741 

765 
766 

2,095 
2,081 

2,128 
2,071 

766 

765 

60,824 

107,667 

24,324i 

27,516i 

765 

765 

64,417 

97,356 

63,987 

765 

765 

765 

765 

765 

765 

778,043 

Left 

Ophthalmoscopic: 

Right  

762 
763 

763 
764 
764 
764 

764 
764 

3 
2 

2 

1 
1 
1 

1 

1 

99.6 
99.7 

99.7 
99.9 
99.9 
99.9 

99.9 
99.9 

A 

Left 

.3 

q 

History  of  ear  trouble: 

a 

b 

1 

c 

1 

d 

1 

Appearance  of  membrani  tympani: 

.1 
1 

Left 

Watch: 

Right /30 

Voice: 

Left     

Right 

744 
746 

601 
598 
720 
765 



21 
20 

164 

167 

45 

97.3 
97.4 

78.6 
78.2 
94.1 
100 

2.7 
2.6 

21   4 

Left » 

Tonsils: 

Right 

Left 

21.8 
5.9 

Condition  of  Eustachian  tubes 

Equilibrium: 
a— 

Right 

Left 

b,  1- 

Right 

765 
765 

100 
100 

Left 

b,2- 

Left 

Right 

Left 

c— 

765 
765 





100 
100 

Left 

Weight 

Chest  measurement: 

Expiration 

Respiratory  system 

765 
762 

3 

99.6 

4 

Pulse  rate 

Systolic 

Diastolic 

764 
765 
764 
764 
764 
760 

1 

99.9 

1 

Veins 

1 

1 
1 
6 

99.9 
99.9 
99.9 
99.3 

1 

Digestive  system 

1 

1 

Genito-urinary  system 

7 

1 

1  But  slightly  defective.    Waived  because  of  previous  experience  and  exceptional  ability. 


90 


AIB  SERVICE  MEDIOAL. 


Tablb  II. — Showing  the  results  of  the  physical  emamination  for  aviation  of  a 
consecutive  1,000  men  at  the  examination  unit,  Washington,  D.  C. — Continued. 

REJECTED. 


Number. 

Rate. 

Causes. 

Total. 

Normal. 

Defect- 
ive. 

Total. 

Normal. 

Defect- 
ive. 

Total 

235 

23.5 

Age 

6,636 
235 
235 

335 
335 
335 
386 
209 

24 
100 
100 

100 
100 
100 
1.6 
.9 

20/26 
20/24 

11.4 
11.2 

100 
100 

100 
100 
100 
100 

100 
100 

28.6 

28 

19.4 

18.6 

100 
100 

100 
100 
100 
100 

26.6 
26.6 

100 
100 

2.7 
2.4 

2.7 
2.6 

100 
100 
67.7 
138.8 

31.7 

35.5 
100 
100 

85.1 
128.3 

69.5 
100 
100 
100 
100 
100 
100 
1,018 

StereoscoDic. .............................. 

189 
218 

232 
219 
223 

46 
17 

3 
16 
12 

80.4 
92.8 

98.7 
93.2 
94.9 

19.6 

Color  vision        ........................... 

7  3 

Muscle  balance: 

Hyperphoria 

1.3 

Exophoria 

6.8 

Esophoria 

5.1 

Adc  action ... 

Abduction 

Visual  acuity: 

Rieht 

Left 

Near  point: 

Right 

2,671.5 
3,627.5 

235 
235 

235 
235 
235 
235 

235 
235 

6,714 
6,691 

4,551 
4,373 

235 
235 

235 
235 
235 
235 

6,245 
6,253 

235 
235 

634 
670 

627 
605 

235 

235 

15,920 

33,620 

7,446 

8,3481 

335 

335 

19,990 

30,152 

16,334 

235 

235 

235 

335 

235 

235 

239,377 

Left        

Ophthalmoscopic: 

Right 

223 
223 

231 
233 
233 
232 

231 
230 

12 
12 

4 
3 
3 

3 

4 

5 

94.9 
94.9 

98.3 
99.1 
99.1 
98.7 

98.3 
97.9 

5.1 

Left 

6.1 

History  of  ear  trouble: 

a 

1.7 

b  

.9 

e  

.9 

d        

1.3 

Appearance  of  membrani  tympanl: 

Rieht..  ..! 

1.7 

Lett         

2.1 

Watch: 

Rieht /30 

Left    /30 

Voice: 

Right 

Left      

Condition  of  nares: 

Right 

231 
331 

205 
205 
226 
235 

4 
4 

30 

30 

9 

98.3 
98.3 

87.2 
87.2 
96.2 
100 

1.7 

Left 

1.7 

Tonsils: 

Rieht        

12.8 

Left 

12.8 

Presftnce  of  adenoids 

3.8 

Condition  of  Eustachla    tubes 

Equilibrium: 
a— 

Right 

Left 

b.l- 

Rlght 

333 
233 

2 
2 

99.1 
99.1 

.9 

Left 

.9 

b,2- 

Right 

Left 

b,3- 

Right 

Left 

o— 

Right 

332 
229 

3 
0 

98.7 
97.4 

1.3 

Left 

2.6 

Height 

Weight 

Chest  measurement: 

Expiration 

Inspiration 

Respiratory  system 

333 
330 

3 

5 

98.7 
97.9 

1.3 

Bones  and  joints 

2.1 

Pulse  rate 

Systolic 

Diastolic 

Heart 

22S 
234 
235 
220 
333 
332 

7 

1 

97 
99.6 
100 
97.4 
99.1 
98.7 

3.0 

Veins 

.4 

Hemorrhoids 

Digestive  system 

6 
2 
3 

2.6 

Hernia 

.9 

Genito-urinary  system 

1.3 

Urinalvsis.  sDeciflc  eravity 

AIB  SEEVIOE  MEDICAL. 


91 


Of  the  235  rejections,  149  were  defective  In  vision,  51  in  tlie  ear  and  equi- 
librium tests,  and  35  failed  to  come  up  to  the  physical  requirements. 

Table  3  gives  the  three  main  groups  and  their  subdivisions,  with  rate  per 

1,000;  showing  that  15  per  cent  of  the  1,000  examined   (over  one-half  of  the 

total  number  rejected)   were  disqualified  on  vision;  5.1  per  cent  on  ear  and 

equilibrium  tests,  and  3.5  per  cent  on  physical  counts.     Equilibrium  alone  was 

the  cause  of  rejection  of  3.3  per  cent,  and  equilibrium  in  combination  with 

other  counts,  4.8  per  cent. 

,» 

Table  III. — Showing  the  three  main  groups,  and  their  aubdivisions  with  rates. 


Causes  of  rejection. 


Total. 


Eye. 


Stereoscopic 

Color  vision 

Muscle  balance  (one  of  which  had  double  vision) 

Field  of  vision 

Visual  acuity  (seven  of  which  had  defective  near  point) . 

Near  point 

Lesions  of  the  fimdus 

Stereoscopic  and  muscle  balance 

Visual  acuity  and  stereoscopic 

Visual  acuity  and  muscle  balance 

Visual  acuity  and  fundus 

Visual  acuity  and  color  blindness 

Visual  acuity  and  hearing 

Visual  acuity  and  equilibrium 

Visual  acuity,  muscle  balance,  and  fundus , 

Visual  acuity,  muscle  balance,  and  stereoscopic 

Ear  and  equilibrium 

Ear 

Ear  and  hernia 

Ear  and  chronic  purulent  otitis  media 

Ear  and  equilibrium 

Equilibrium 

Equilibrium,  hay  fever,  and  defective  static  sense 

Equilibrium,  result  of  injury  to  head  in  motor  accident. 
Physical 

Heart 

Lungs 

Lungs  and  hay  fever 

Weight 

Bones  and  joints 

Hernia 

Teeth 

Urinalysis 

Varicose  veins 

Stammering 


Number. 


235 


149 
8 

15 

13 
2 

63 
4 
7 
0 
5 
5 
3 
2 
3 

10 
1 
2 

51 

10 
1 
2 
5 

31 
1 
1 

35 
8 
3 
1 

11 
2 
3 
2 
4 
1 
1 


Rate. 


} 


23.5 


15.0 
0.8 
1.5 
1.3 
0.2 
6.3 
0.4 


0.7 
0.6 
0.5 
0.5 
0.3 
0.2 
0.3 
1.0 
0.1 
0.2 
5.1 

1.3 

0.5 

3.3 

3.5 

0.8 

0.4 

1.1 
0.2 
0.2 
0.2 
0.4 
0.1 
0.1 


92 


AIE  SERVICE  MEDICAL. 


S 

^        1 


1        1 

s 

E 


II 


I 

s 


04 


g 


tcoito 

J 


OO  Wi-l»J  CO 


•^i 


CI 
m 

■3 
o 

;2; 


;:?  = 

O    I 

>  ■ 

.2  ■-* 

CO   « 


.2  + 


o 
a.5 


|-i 


•a  3 


I 

O 

3  5" 

C     . 


m 


:;:;  —  o 

9  !=  S 


c  a  a 
5  2.2 

^  '-M  *-*5 
c5  c!  rt 

bM    !-•    ^ 

o  05  03 

ooo 


2  a 

03  03 

23 »  2  e 

■*-*  C3  *^  ** 

e  .2"  c  '5. 

O  c«  O  O 

c3  c3  !^  o 
bri  ^  b^  u 

OtDOoa 


6 
£;'•>- 

1-  o  o  — 

S  >-  >-  i: 

e  C  O  o 
P  o  oj~ 
u  -^  -^  ^ 

O  W.  1-  S* 

■J-;  O)   03    t 

ojOO^ 


P. 
o 
o    . 

rr  — * 
O  C3 

fe'S) 

-*^  — 
D  o 

"3'S 

03   03 


S 


9  1= 
o  o 


o  o 


OO 


CO  ;r  CO 
w  03  ■*^ 

•2^S.2 

-O  ^-  ^ 

2  ?<  C3 

p^  K  *-• 

-a    M    a> 

3  3  & 


tt) 


03  ;:3 


oooSoooooocoooooooooooooooooooooooooooooooo 


AIE  SEEVICE  MEDICAL. 


93 


•s 
e 

o 


fti 


.  •  .  ."^  • 

(O  o  «  <a  c  S 

OJ  M  M  t»  ^  tq 

W  OT  w  X  .-^  M 

ea  c3  c3  cJ  »J^c3 

(1,  (I,  fL,  Oh  05  Ph 


.  3 


•ri  o  r^  oc  oi  Q 

ssssss 


Table  1.— Giving  an  example  of  the  methods  used  in  posting  the  results  of  the  examination,  and  containing  the  numbers  oj  the  first  50  men  of  the  1,000  consecutively  examined. 


2 

9 

10 

11 

12 

13 

14 

15 

IS 

17 

18 

20 

22 

23 

24 

25 

28 

29 

30 

31 

32 

i 
t. 

n 

^ 

Muscle  balance. 

Visual  acuity. 

Near  point. 

Ophthal- 
raospopic. 

History  of  car  trouble. 

Appear- 
ance of 
mom- 
broni 
tym- 

(c) 

Condi- 
tion of 
nares. 

Tonsils. 

f 

1 
■3 

1 

Equilibrium. 

Chest 
measure- 
ment. 

1 
& 
& 

2 
1 
1 

N. 

(a) 

(c) 

(d) 

(e) 

(0 

1 

1 

\ 

a 

i 

Watch. 

Voice. 

A. 

b. 

C. 

ID 

1 

1 

a 

< 

20 
26 
21 
SO 
fS 
23 

N. 
N. 
N. 
W. 
if. 
N. 
N. 
N. 
N. 
JV. 
N. 
N. 
N. 
N. 
N 

6 

N. 
N. 
N. 
if. 
if. 
N. 

n 

d 
M 

s 

< 

pani. 

J^ 

f- 

2 

3 

1 

2 

1 

1 

b    . 

'°>2 

'U 
37* 

s 

N. 

84 

m 

s 

1 

□ 

1 
1 

s 

1 

1 

1 

1" 

0 

1 

K. 

L. 

B. 

L. 

H. 

L. 

(a) 

No. 

(i) 

No. 

(4) 

E. 

L. 

R. 

L. 

R. 

L. 

R. 

L. 

R. 

L. 

R. 

L. 

R. 

L. 

E. 

L. 

R. 

I.. 

R. 

L. 

1 

»i.. 

02.. 
03.. 
94.. 
Jfi.. 
06.. 

o;  . 
m.. 

09.. 
10.. 
11-- 
12.. 
13.. 
14.. 
15.. 
16.. 
17.- 
18.. 
19.. 
20.. 

N 

N. 

N 

20/20 

20/20 

9 

9 

N. 

N. 

No. 

No, 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

1'. 

27 

27 

T. 

T. 

2 

2 

2 

2 

R. 

69 

133 

33 

142 

90 

N. 

N. 

N. 

N. 

No. 

N. 

1.018 

Set  itSd 
tin 

1001 

n" 

n" 

N 

20/20 

20/20 

15 

15 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

P. 

28 

25 

T. 

T. 

2 

2 

2 

2 

R. 

05 

lis 

32 

37i 

N. 

N. 

96 

120 

82 

N. 

N. 

No. 

N. 

No. 

N. 

1.018 

1002 

if. 

if. 

if. 

;X!'!!.!; 

20/20 
gOliO-t 

20/20 
SOISO 

9 
10 

9 

to 

N. 
if. 

N. 

if. 

No. 
ifo. 

No. 
ifo. 

No. 
ifo. 

No. 

Jfo. 

N. 

if. 

N. 
if 

30/30 

SOISO 

30/30 

H6IS0 

20 

SO 

20 
SO 

N. 
if. 

N. 
if. 

N. 
if. 

N. 
if. 

No. 
Ifo. 

P. 
P. 

27 

se 

2.^ 

te 

T. 
T. 

T. 
T. 

2 
£ 

2 

e 

3 
3 

3 
£ 

R. 
R. 

L. 

65 
66 

126 
110 

32 

354 
SS' 

N. 
AT. 

N. 
If. 

82 
8£ 

136 
ItO 

80 
80 

N. 

Ai. 

N. 
iV. 

No. 
ATo. 

N. 

No. 
ifo. 

N. 
AT. 

1.018 
1.019 

1003 

tit' 

•t^ 

iv' 

if' 

if 

1 

SQItO-t 

soieo 

10 

to 

if. 

if. 

Wo. 

ifo. 

ifo. 

ifo. 

A'. 

if. 

SOISO 

SOISO 

so 

to 

if 

if. 

N. 

AI. 

ifo. 

P. 

14 

SO 

T. 

T. 

1 

T. 

1 

i>PJi. 

R. 

Ij 

89 

170 

35 

SS 

Ai. 

AI. 

7£ 

tie 

70 

if. 

N. 

Aio. 

N. 

Ifo. 

Ai. 

l.OSO 

to 

N." 

N.' 

N. 

....|..... 

20/20 

20/20 

9 

9 

N. 

N. 

No 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

'20 

N. 

N. 

N. 

N. 

No. 

P. 

25 

23 

T. 

T. 

3 

2 

2 

2 

R. 

L. 

C5 

136 

30 

35) 

N. 

N. 

72 

132 

Si 

AI. 

N. 

No. 

N. 

Aio. 

Ai. 

1.016 

1006 

22 
2.') 

n! 

N. 

N. 

N. 

20/»l 

20/20 

10 

10 

N. 

N. 

No. 

No. 

No. 

No. 

N, 

N. 

30/30 

3030 

20 

20 

N. 

N. 

« 

* 

No. 

P. 

29 

32 

T. 

T. 

3 

2 

3 

2 

R. 

L. 

68 

148 

32 

35) 

N. 

N. 

68 

130 

86 

N. 

N; 

No. 

N. 

No. 

N. 

1.019 

io 

1007 

N, 

N. 

N. 

N. 

20/20 

20/20 

10 

10 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

P. 

28 

25 

T. 

T. 

2 

2 

3 

3 

R. 

L. 

68 

132 

32 

37) 

N. 

N. 

84 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.017 

1008 

2S 

n! 

N. 

N. 

N. 

20/20 

20/20 

9 

9 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

* 

* 

No. 

P. 

35 

29 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

08 

138 

311 

30 

N. 

N. 

76 

130 

82 

N. 

N. 

No. 

N. 

No. 

N. 

1.018 

io 

1009 

S7 

if 

N. 

if. 

if 

SOItO-l 

soim 

9 

S 

if. 

if. 

ifo. 

ifo. 

ifo. 

ifo. 

if 

if. 

SO}SO 

SOISO 

SO 

20 

If. 

if. 

if. 

N. 

Aio. 

P. 

SO 

ta 

T. 

T. 

S 

£ 

« 

8 

fi. 

L. 

67 

167 

SS 

SO) 

AT. 

if. 

7£ 

ISO 

80 

if. 

Ai. 

Aio. 

* 

Afo. 

if. 

LOSS 

ll-«9 

1010 

25 

N." 

N. 

N. 

N. 

20/20 

20/20 

9i 

91 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N 

N. 

N. 

No. 

P. 

20 

20 

T. 

T. 

2 

2 

3 

2 

R. 

L. 

70 

146 

31 

36 

N. 

N. 

78 

140 

90 

N. 

N. 

No. 

N. 

No. 

N. 

1.017 

1011 

24 

n! 

N. 

N. 

N. 

20/15 

20/15-1 

12 

12 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

^ 

N. 

N 

N. 

N. 

No. 

P. 

18 

17 

T. 

T. 

2 

2 

3 

3 

H. 

L. 

65 

121 

2SJ 

33) 

N. 

N. 

96 

130 

84 

N. 

N. 

No. 

N. 

No. 

N. 

1.018 

1012 

27 

n' 

N. 

N. 

N. 

20/16-1 

20/16-1 

13 

.  13 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

N. 

N. 

N. 

N. 

No. 

P. 

20 

27 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

08 

152 

33 

36'' 

N. 

N. 

8S 

148 

90 

N. 

N. 

No. 

N. 

No. 

N. 

1.017 

1013 

22 

n" 

N. 

N. 

N. 

'.y.y.'.'.'.'. 

20/15-1 

20/20+3 

8 

» 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

P. 

25 

26 

T. 

T. 

2 

2 

2 

2 

R. 

L. 

67 

12S 

30J 

35 

N. 

N. 

84 

124 

70 

N. 

N. 

No. 

N. 

No. 

N. 

1.017 

1014 

25 

N 

N. 

N. 

N. 

20/15-1 

20/15-2 

12 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

* 

* 

No. 

P. 

21 

23 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

65 

103 

34 

37) 

N. 

N. 

84 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.017 

1015 

29 

N 

N 

N. 

N. 

N. 



20/15-1 

20/15-1 

12 

12 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

1'. 

28 

20 

T. 

T. 

2 

2 

3 

3 

R. 

L. 

66 

136 

31i 

.35 

N. 

N. 

72 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.020 

io' 

1016 

25 

n! 

N 

N. 

N. 

N. 

20/15-1 

20/15-1 

11 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

* 

* 

No. 

P. 

21 

22 

T. 

T. 

2 

3 

2 

2 

R. 

L. 

65 

115 

27. 

30i 

N. 

N. 

96 

120 

70 

N. 

N. 

No. 

N. 

No. 

N. 

1.019 

10 

1017 

21 

n' 

N 

N. 

N. 

N. 

20/14-2 

20/15-4 

11 

12 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

* 

* 

No. 

P. 

20 

25 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

66 

ISC 

30 

41 

N. 

N. 

75 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.019 

16 

1018 

22 

n! 

N. 

N. 

N. 

N. 

20/15-1 

20/15-2 

11 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

* 

* 

N. 

N. 

No. 

P. 

29 

28 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

67 

126 

30 

33) 

N. 

N. 

90 

125 

90 

N. 

N. 

No. 

N. 

No. 

N. 

1.019 

15 

1019 

22 

n'. 

N 

N. 

N. 

N. 

20/15-1 

20/15-1 

loi 

9 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20- 

N. 

N, 

N. 

N. 

No. 

P. 

10 

16 

T. 

T. 

2 

2 

2 

2 

R. 

I,. 

69 

140 

32 

30 

N. 

N. 

84 

136 

78 

N. 

N. 

No. 

N. 

No. 

N. 

1.016 

1020 

il 

24 

n! 

N. 

N. 

N. 

N. 

20/15-1 

20/15-3 

11 

10 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

♦ 

* 

* 

P. 

35 

30 

T. 

T. 

4 

3 

1 

4 

R. 

L. 

72 

148 

30 

35 

N. 

N. 

78 

lis 

78 

N. 

N. 

No. 

N. 

No. 

N. 

1.020 

'20^17-16' 

1021 

i2  " 

22 

n' 

N. 

N, 

N. 

N. 

20/15 

20/15-2 

11 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N.. 

No. 

P. 

20 

25 

T. 

T. 

3 

3 

3 

4 

R. 

L. 

68 

112 

29 

32) 

N. 

N. 

80 

126 

78 

N. 

N. 

No. 

N. 

No. 

N. 

1  1.009 

32 

1022 

S4- 
25.. 

26 
Si 
21 

if. 

N 

N. 

if. 
N. 

N, 
if. 
N. 

N. 
if. 
N. 

N. 
if. 
N. 

20/20 

SOISO-S 

20/15 

20/20 

SOIlO-l 

20/1.'! 

11 

10 

11 

11 
10 
11 

N. 

if. 
N. 

N. 
if. 
N. 

No. 
Ifo. 
No. 

No. 
ifo. 
No. 

No. 
ifo. 
No. 

No. 
ifo. 
No. 

N. 
If. 
N. 

N. 
if 
N. 

30,'30 
SOISO 
30/30 

30,30 
SOISO 
30/30 

20 
» 
20 

20 
SO 
20 

N. 
if 
N. 

N. 
A'. 

N. 

* 
Ai. 
N. 

If. 
N. 

No. 
m. 
No. 

P. 
P. 
P. 

24 
18 
19 

24 

le 

17 

T. 

r. 

T. 

T. 
T. 
T. 

3 
3 
2 

3 
3 
3 

3 
£ 
2 

4 
3 
2 

R. 

K. 
R. 

1-. 
L. 
L. 

04 

as 

68 

130 
ISl 
129 

33 

S.I 
30 

30 
Si 
34J 

N. 
Ai. 
N. 

N. 

AT. 
N. 

72 
Si 
84 

120 
ISO 
128 

80 
74 
82 

N. 

Ai. 
N. 

N. 
A-. 
N. 

No. 
ifo. 
No. 

N. 
Ai. 
N. 

No. 
Aio. 
No. 

N. 
N. 

1.018 
1.016 
1.019 

10 
J-ll-Sl 

1023 

1084 

1025 

PC. 

SI 

if 

if. 

if. 

if. 

if. 

taiis-i 

llll'i-l 

iO 

10 

N. 

if. 

ifo. 

ifo. 

ifo. 

ifo. 

if. 

If. 

SOISO 

SOISO 

to 

to 

if 

IV. 

Ai. 

AT. 

Aio. 

P. 

S4 

Si 

T. 

T. 

* 

« 

4 

i 

R. 

i. 

a 

IS! 

31 

Si', 

N. 

Ai. 

SS 

ISO 

SO 

If. 

AT. 

No. 

If. 

Ifo. 

Ai. 

l.OIS 

'isi 

1«8 

27.. 

23 

N 

N. 

N. 

N. 

N. 

20/15 

20/15 

11 

11 

N. 

N, 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

• 

» 

No. 

P. 

20 

21 

T. 

T. 

2 

2 

3 

3 

R. 

L. 

65 

148 

31 

35) 

N. 

N. 

72 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.020 

16 

1027 

2« 

22 

N 

N. 

N. 

N. 

N. 

20/15 

20/15 

11 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N 

♦ 

* 

No. 

P. 

17 

17 

T. 

T. 

2 

3 

3 

3 

R. 

L. 

68 

155 

31i 

30J 

N. 

N. 

72 

120 

80 

N. 

N. 

No. 

N. 

No. 

N. 

1.016 

16 

1028 

tfS.. 

SS 

if. 

if. 

if. 

if. 

if. 

::::: 

«0/io-I 

SOIIS-f 

It 

li 

If. 

If. 

ifo. 

Ifo. 

ifo. 

ifo. 

if. 

If. 

SOISO 

SOISO 

to 

to 

if. 

if. 

if. 

if. 

m. 

P. 

SS 

SO 

T. 

T. 

S 

S 

3 

3 

R. 

L. 

69 

119 

30 

Si 

Ai. 

* 

100 

IK 

SO 

N. 

AT. 

A-o. 

N. 

No. 

if. 

i.oto 

ts 

iota 

CO.. 

25 

N. 

N. 

N. 

N. 

N. 

20/20 

20/20 

11 

11 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

P. 

18 

18 

T. 

T. 

3 

3 

3 

3 

R. 

L. 

72 

157 

34 

39 

N. 

N. 

80 

120 

75 

N. 

N. 

No. 

N. 

No. 

N. 

1.020 

vao 

ei 

21 

» 

N. 

N. 

N. 

N. 

'.'.'.'.'. 

20/10-5 

20/10-3 

10 

10 

N. 

N. 

No. 

No. 

No. 

No. 

N. 

N. 

30/30 

30/30 

20 

20 

N. 

N. 

N. 

N. 

No. 

P. 

21 

22 

T. 

T. 

3 

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27 

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32 

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80 

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lOSO 

89118—10.     (To  follow  page  93.) 


1  Marked  trace  oF  albumin. 

Note  (a), — For  key  to  Table  I,  refer  tu  t'xamination  blank  used  by  units. 

Note  (b).— Uyperpliorla  not  over  1°  entaed  as  normal:  esopboria  and  exopboria  not  over  2°  entered  as  normal 


ectUively  examined. 


23 

24 

25 

28 

29 

30 

31 

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31 

2 

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125 

75 

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80 

78 

120 
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82 

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m 

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84 

126 

82 

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16 

1036 

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N. 

N. 
N. 

72 

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120 
lie 

80 
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1.018 

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130 

80 

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31 

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81 

125 

80 

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120 

80 

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90 

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120 
130 
128 
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80 
70 
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N. 
N. 
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No. 
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No. 
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1046 

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31 

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36 

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No. 

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1.017 

1050 

CHAPTER  VI. 

REPORT  OF  MEDICAL  OFFICERS  JUST  RETURNED  FROM 
ENGLAND,  FRANCE,  AND  ITALY— JANUARY  28,  1918. 


PREFACE. 


Wlicther  or  not  "Aviation  will  win  the  war,"  as  so  many  authorities 
state,  we  at  least  know  one  fact  positively,  and  this  fact  makes  clear 
the  function  and  purpose  of  the  Medical  Department  of  our  Aviation 
Service — we  should  and  must  keep  the  fighting  force  of  our  Aviation 
Service  at  its  highest  degree  of  efficiency. 

The  British,  at  the  end  of  the  first  year  of  the  war,  found  to  their 
astonishment  that  of  the  total  number  of  accidents  to  their  fliers,  65 
per  cent  were  due  to  physical  defects  of  their  pilots.  They  at  once 
realized  the  need  of  expert  medical  study  of  their  fliers.  The  next 
year  the  rate  was  20  per  cent  and  the  next  year  12  per  cent. 

The  medical  problem  of  aviation  consists  of: 

(1)  The  selection  of  the  flier. 

(2)  The  care  of  the  flier.    This  includes  (a)  classification  of 

the  pilot,  and  (&)  maintenance  of  efficiency  in  actual 
service. 

The  selection  of  the  flier  in  the  United  States  was  accomplished  by 
the  work  of  G7  physical  examining  units,  which,  in  the  course  of  little 
over  seven  months,  have  examined  thousands  of  applicants. 

In  order  to  study  the  conditions  abroad  and  to  learn  the  methods 
of  the  Aviation  Service  of  the  Allies,  medical  officers  concerned  in 
the  development  of  our  service  were  sent  to  England,  France,  and 
Italy.  Our  methods  of  examining  candidates  in  the  United  States 
and  our  plans  for  the  care  of  the  flier,  both  at  home  and  abroad,  were 
submitted  to  all  the  experts  of  the  British,  French,  and  Italian  forces, 
and  have  met  with  unreserved  approval.  It  was  surprising  to  hear 
the  same  statement  reiterated  by  the  British,  French,  and  Italians — 
"  It  is  very  fortunate  that  the  Air  Forces  of  the  United  States  are 
profiting  by  the  mistakes  of  our  flying  service  in  recognizing  at  the 
beginning  that  the  medical  problem  of  Aviation  is  a  very  special 
problem  and  can  not  possibly  be  conducted  except  by  an  organized 
body  of  experts." 

The  most  essential  feature  of  the  present  plan  for  the  CARE  of  the 
Aviator  is  the  selection  of  medical  officers  who  will  act  as  ADVISORS 
89118—19 7  95 


96  AIB  SERVICE  MEDICAL. 

to  the  commanding  officers  of  flying  schools  and  squadron  groups. 
Such  medical  advisors  are  to  be  selected  from  those  who  have  been 
most  familiar  with  the  examination  of  the  applicants  for  the  Avia- 
tion Service,  and  before  undertaking  these  duties  they  should,  in 
addition,  have  undergone  a  special  course  of  training  under  the 
direction  of  the  Research  Board  of  this  department.  This  training 
will  equip  them  to  furnish  the  commanding  officers  with  reliable 
daily  information  as  to  the  physical  fitness  of  the  individual  fliers 
in  their  commands. 

Research  work  can  also  be  carried  out  in  certain  large  flying  schools 
in  France,  and  it  is  here  that  the  preliminary  work  done  in  the  United 
States  can  find  its  practical  application  in  field  service. 

Interviews  with  British,  French,  and  Italian  fliers  made  clear 
that  they  considered  it  a  most  excellent  plan  to  have  a  medical 
advisor  attached  to  squadron  groups;  they  frankly  stated  that  if 
such  supervision  had  been  possible  in  the  early  days  of  their  service, 
many  hundreds  of  fliers  would  have  been  saved.  We  believe,  and 
this  belief  is  confirmed  by  the  unanimous  opinion  of  those  in  charge 
of  the  British,  French,  and  Italian  services,  that  such  supervision 
of  the  physical  welfare  of  the  flier  will  reduce  to  a  minimum  fatalities 
and  accidents  in  our  Air  Service. 

GENERAL  STATEMENT. 

It  is  only  in  the  last  two  years  that  serious  consideration  has  been 
given  to  the  importance  of  medical  supervision  of  all  that  pertains 
to  aviators.  As  esLvly  as  1910,  Germany  had  made  some  study  and 
published  a  definite  form  of  examination  for  those  wishing  to 
qualify  as  pilots  in  the  aeronautical  services  of  their  country.  As  far 
as  is  known,  no  serious  study  was  being  made  on  any  large  scale  in 
any  other  country.  In  1914,  a  board  of  medical  officers  drew  up  a 
form  for  the  physical  examination  of  officers  of  the  Regular  Army 
who  wished  to  transfer  to  the  Aviation  Section  of  the  Signal  Corps. 
As  the  applicants  were  confined  entirely  to  regular  officers  who  had 
previously  been  physically  examined,  the  type  of  the  examination 
was  made  largely  one  of  selecting  men  with  special  qualifications  for 
flying.  Special  stress  was  laid  upon  visual,  aural,  and  cardiac 
conditions. 

In  1916,  after  two  years  of  war,  it  was  seen  by  the  various  coun- 
tries engaged,  as  well  as  the  United  States,  that  physical  defects  were 
of  great  importance  in  the  causation  of  air  accidents.  The  British 
services  at  this  time  were  not  laying  special  stress  upon  rejecting 
candidates  for  flying  positions  because  of  physical  defects.  In  1916, 
however,  they  realized  that  it  was  necessary  to  make  a  careful  selec- 
tion of  candidates  in  order  to  have  efficient  flying  forces.     Gradually 


AIB  SEBVIOE  MEDICAL.  97 

they  have  elevated  their  standards,  guided  by  practical  experience 
in  the  flying  and  air  fighting,  especially  in  Flanders. 

Both  the  French  and  Italian  air  services  have  expert  examiners, 
whose  sole  duty  it  is  to  select  from  the  applicants  men  physically 
fit  for  service  in  the  air.  In  fact,  in  all  the  armies  of  the  Allies  (ex- 
cept the  Russian,  about  which  we  have  no  definite  information)  there 
have  been  established  research  boards  consisting  of  medical  experts 
who  have  devoted  all  their  time  to  the  spefcial  problems  of  Aviation. 

As  stated  in  the  preface,  the  medical  problem  in  Aviation  is  divided 
into  two  parts:  (1)  The  SELECTION  of  the  flier,  and  (2)  the 
CARE  of  the  flier. 

THE  SELECTION  OF  THE  FLIEE. 

This  is  accomplished  in  the  United  States  by  the  work  of  67  ex- 
amining units  with  a  personnel  of  over  500  physicians.  In  charge 
of  each  unit  there  are  one  or  more  commissioned  officers  who  have, 
for  many  months,  spent  all  their  time  in  studying  this  subject.  In 
establishing  these  units,  it  has  been  impressed  on  these  officers  that 
they  are  not  only  to  examine  candidates,  but  are  to  take  this  oppor- 
tunity to  prepare  themselves  for  the  care  of  the  flier  with  the  Ex- 
peditionary Forces  at  the  front  and  at  the  flying  schools  in  Europe. 

THE  GERMAN  SERVICE. 

For  obvious  reasons  full  details  are  not  available,  but  we  do  know 
the  essential  points,  having  learned  them  from  German  prisoners. 
The  Germans  have  a  specially  organized  medical  service  for  the  study 
of  the  flier.  Every  individual  aviator  goes  through  his  original  ex- 
amination all  over  again  once  a  month.  In  this  way  the  Germans 
are  able  to  keep  their  air  flying  force  at  its  highest  efficiency  by 
keeping  in  continual  touch  with  the  mental  and  physical  condition 
of  each  aviator.  This  REEXAMINATION  OF  THE  FLIER  is 
an  essential  part  of  our  proposed  plan.  Those  medical  officers  in 
the  United  States  who  are  most  fitted  for  this  work  (and  they  include 
a  large  number  of  the  highest-grade  physicians  and  specialists  in 
the  United  States)  can  be  selected  and  sent  abroad  in  increasing 
numbers  according  to  the  requirements  of  our  service  in  Europe; 
they  are  fully  trained  and  equipped  by  months  of  previous  study  in 
the  EXAMINATION  of  the  flier  to  apply  the  same  standards  and 
the  same  methods  in  the  study  and  care  of  the  flier. 

For  example,  medical  advisors  serving  with  the  British  forces  at  the 
front  realized  that  there  was  much  more  demanded  of  the  medical 
service  than  the  physical  selection  of  pilots,  or  the  sanitary  and 
medical  control  such  as  would  be  furnished  to  other  branches  of  their 
army.    They  realized  that  the  very  nature  of  the  services  of  the 


98  AIB  SEBVICE  MEDICAL. 

flyin^r  officer  was  snch  as  to  demand  special  supervision  at  all  times. 
They  found  as  follows: 

Aviation  presents  new  physiological  and  pathological  problems  which  reqxilre 
special  study,  and  which  can  only  be  dealt  with  satisfactorily  by  a  specially 
trained  body  of  medical  men.  Medical  officers  who  are  only  familiar  with  the 
ailments  of  nonflying  men  can  not,  without  previous  and  special  study  of  the 
matter,  properly  deal  with  or  understand  the  conditions  which  may  arise  in 
aviators.  For  example,  greatly  rarified  air  at  high  altitudes,  with  the  con- 
sequent difficulty  of  getting  a  sufficient  supply  of  oxygen  for  the  needs  of  the 
body,  produces  a  number  of  conditions  of  importance  and  gravity  which  are 
being  studied  actively  at  the  present  time.  Flying  at  high  altitudes  or  for 
a  long  period  without  proper  precautious  has,  on  account  of  the  great  strain 
Involved,  serious  effects  not  only  on  the  cardio-vascular  system,  but  also  on 
the  muscular  and  nervous  systems.  So  far  our  knowledge  of  these  matters 
and  of  the  best  methods  of  dealing  with  them  is  still  in  quite  an  early  stage. 
Nevertheless,  in  certain  directions,  some  points  have  already  been  made  out 
which  have  proved  of  great  practical  importance  In  the  selection  of  flying 
officers,  in  obviating  some  of  the  special  risks  referred  to  above,  and  in  watch- 
ing and  treating  these  officers.  For  example,  as  regards  the  admission  bf  cadets, 
the  tests  suitable  for  a  flying  officer  differ  in  some  respects  from  those  necessary 
for  officers  who  do  not  fly.  Thus,  accuracy  of  sight  is  most  essential  to  the 
flying  officer,  particularly  for  fighting,  observing,  and  landing,  whilst  a  certain 
amount  of  disability  of  the  lower  limbs  may  not  necessarily  debar  a  man  from 
being  an  efficient  aviator,  though  it  would  probably  completely  incapacitate  him 
for  the  other  services.  These  points  could,  no  doubt,  be  quickly  grasped  by 
any  medical  man,  but,  in  addition  to  them,  the  cadet  must  be  specially  ex- 
amined as  to  the  heights  to  which  he  can  ascend,  with  or  without  an  artificial 
supply  of  oxygen.  Perhaps  the  point  in  which  the  special  education  of  the 
medical  officer  is  most  necessary  is  in  the  daily  care  and  watchfulness  over 
the  aviator.  The  fl.ving  officer  is  a  most  valuable  man,  and  as  the  result  of 
the  effects  of  high  altitudes  and  variations  in  the  amount  of  oxygen,  and  of 
the  severe  nervous  and  muscular  strain  to  which  he  is  constantly  subjected, 
he  Is  more  easily  incapacitated  than  officers  In  any  of  the  other  services. 
Hence  he  needs  very  special  and  constant  attention  as  to  his  diet,  exercise, 
and  habits,  which  should  be  carefully  regulated.  He  should  be,  from  time  to 
time,  examined  both  immediately  after  a  flight  and  also  after  he  has  had  a 
rest  from  flying.  Note  must  be  made  of  the  condition  of  his  heart  and  of  his 
nervous  and  muscular  systems,  especially  in  connection  with  the  altitude 
which  he  has  attained  and  the  length  of  time  he  has  been  in  the  air. 

This  examination  is  necessary  so  that  the  medical  officer  may  be  able  to  or- 
der rest  and  treatment  in  cases  where  a  flying  officer  shows  signs  of  becom- 
ing stale  or  of  breakdown.  If,  on  the  one  hand,  this  is  not  properly  attended 
to,  it  is  certain  that  a  large  number  of  officers  will  go  on  flying  long  after 
they  ought  to  have  been  resting,  and  may  thus  become  permanently  incapaci- 
tated for  flight.  If,  on  the  other  hand,  these  officers  are  carefully  watched, 
as  stated  above,  and  placed  under  treatment  as  soon  as  there  is  any  sign  that 
they  are  suffering  from  stress  of  flying,  they  may  go  on  for  a  long  time  with- 
out becoming  permanently  unfit,  and  in  this  way  the  great  wastage  of  flying 
personnel  which  now  occurs  may  be  largely  prevented.  The  skill  necessary 
for  the  medical  examination  and  treatment  of  flying  officers  and  men,  as 
described  above,  can  only  be  obtained  by  special  training  and  constant  prac- 
tical experience  of  the  effects  of  flying. 


ATR  SEEVICE  MEDICAL.  99 

To  mention  one  more  example,  it  is  found  that  in  certain  individnals  who 
may  have  apparent  perfect  acuity  of  vision,  there  exists  a  lacl£  of  ability  to 
make  use  of  both  eyes,  which  interferes  with  judgment  of  distance;  this 
disability  tends  to  Increase  under  the  strain  of  aviation,  and  to  result  in  bad 
landings,  "  crashes,"  and  consequent  loss  of  personnel  and  material.  There  is, 
however,  some  evidence  that  this  condition  can  be,  and  has  been,  cured  by 
specially  skilled  and  practiced  medical  officers. 

In  the  spring  of  1916  it  was  seen  that  tjie  physical  examination  re- 
quired of  the  United  States  Army  for  the  Aviation  Section,  Signal 
Corps,  needed  revision.  While  the  character  of  the  examination  was, 
in  general,  satisfactory,  there  was  a  lack  of  definite  stanclards  which 
made  its  practical  application  on  a  large  scale  impossible.  It  was 
realized  at  this  time  that  the  examination  had  to  be  shortened  and 
that  only  trained  men,  proficiently  qualified,  should  make  these  ex- 
aminations. In  May,  1917,  the  revision  of  this  examination  form  was 
completed  and  put  into  operation  and  officially  authorized.  Hospi- 
tals with  well-equipped  medical  staffs  were  selected  in  each  of  the 
largest  cities  of  the  United  States,  and  designated  as  examining  units 
to  carry  out  these  examinations.  Within  a  month,  some  20  of  these 
units  had  been  established,  each  unit  capable  of  examining  on  an 
average  of  30  candidates  a  day.  The  succeeding  month,  the  number 
of  these  units  was  increased  till,  at  the  present  time,  there  are  some  67 
examining  units  in  the  United  States  with  the  capacity  of  examining 
a  large  number  daily.  It  is  believed  advisable  to  examine  a  large 
number  of  candidates,  place  them  on  a  waiting  list  until  such  time 
as  the  Air  Service  shall  need  them.  As  the  number  rejected  is  very 
great,  the  total  number  examined  therefore  has  to  be  largely  in  excess 
of  the  actual  needs. 

The  Surgeon  General  of  the  United  States  Army  and  the  Chief 
Signal  Officer  both  realized  that  the  medical  service  attached  to  the 
air  forces  in  the  United  States  needed  more  independence  of  action 
than  would  be  necessary  for  medical  services  attaclied  to  other  arms 
of  the  service.  As  soon  as  the  Aviation  Section,  Signal  Corps,  was 
made  a  separate  service  under  the  general  supervision  of  the  Chief 
Signal  Officer,  a  medical  division  was  authorized  for  the  Aviation 
Section,  Signal  Corps.  A  Chief  Surgeon  was  designated  and  all 
personnel,  supplies,  and  equipment  attached  to  the  Medical  Division 
of  the  Aviation  Se<:tion,  Signal  Corps,  was  placed  directly  under  the 
Commanding  General  of  this  service. 

Paragraph  191,  Army  Kegulations,  1913,  states:  "That  in  the 
United  States  the  commander  of  a  territorial  department  commands 
all  the  military  forces  of  the  Government  within  its  limits,  whether 
of  the  line  or  staff,  except  in  so  far  as  exempted  from  his  control  by 
the  Secretary  of  War.  Among  the  exempted  institutions  are  general 
depots  of  supply  and  all  schools  of  instruction  for  every  branch  of 


100  AIE  SERVICE  MEDICAL. 

the  service,  including  Signal  Corps  aviation  schools  and  the  United 
States  Army  Balloon  School."  The  transfer  of  this  personnel  was 
duly  made,  and  the  relation  of  the  Chief  Surgeon,  Aviation  Section, 
Signal  Corps,  to  the  Surgeon  General  was  placed  on  a  similar  basis 
to  that  of  the  relation  of  the  Chief  Surgeon  of  the  territorial  depart- 
ment to  the  Surgeon  General,  All  medical  problems,  whether  sani- 
tary or  the  study  of  fliers,  come  under  the  direct  supervision  of  the 
Chief  Surgeon,  Aviation  Section,  Signal  Corps. 

In  order  to  carry  further  the  work  of  the  Medical  Department  of 
the  Aviation  Section,  Signal  Corps,  a  Research  Board  was  authorized 
for  duty  in  the  office  of  the  Chief  Surgeon,  to  study  all  phases  of 
flying  which  bore  direct  relation  to  the  mental  or  physical  equipment 
of  the  flier;  such  a  board  has  now  been  in  operation  since  October, 
1917. 

RELATION  TO  FORCES  ABROAD. 

Because  of  the  impossibility  of  visualizing  in  the  United  States 
military  conditions  existing  in  France,  and  as  the  whole  object  of  the 
development  of  the  air  forces  in  the  United  States  was  obviously  for 
the  purpose  of  eventually  having  them  serve  abroad,  it  was  deemed 
urgent  that  medical  officers,  responsible  for  the  development  of  the 
medical  service,  Aviation  Section,  Signal  Corps,  in  the  United 
States,  should  have  an  opportunity  to  see  what  was  actually  taking 
place  at  the  front.  When  it  was  decided  to  send  the  present  Com- 
manding General  Air  Service  in  France  abroad,  two  medical  officers 
were  selected  to  go  with  him  for  temporary  duty.  The  purpose  of 
their  visit  was  to  obtain  all  available  information  relative  to  the 
medical  services  of  the  Allied  Countries  to  find  out  what  policy  was  to 
be  adopted  by  the  Commanding  General  American  Expeditionary 
Forces,  and  then  to  assist  in  every  possible  way  toward  the  organiza- 
tion of  medical  services  under  the  air  forces  for  American  Expedi- 
tionary Forces,  should  such  be  authorized ;  and  to  take  back  the  in- 
formation in  order  to  build  up  the  medical  services.  Aviation  Sec- 
tion, Signal  Corps,  in  the  United  States,  on  lines  suitable  to  the  needs 
abroad.  At  the  present  time  in  the  United  States  medical  officers  are 
being  trained  in  large  numbers  in  the  various  special  duties  which 
they  will  be  required  to  perform  when  it  is  realized  how  essential  are 
their  services  to  the  success  of  the  Air  Forces. 

ENGLISH. 

The  lack  of  oxygen  at  high  altitudes,  the  cause  of  so  many  symp- 
toms complained  of  by  the  flier,  is  responsible  for  the  disability  of 
a  large  percentage  of  pilots.  In  order  to  study  the  oxygen  question, 
we  were  sent  to  Advance  Headquarters,  Royal  Flying  Corps,  British 


AIB  SERVICE   MEDICAL.  -ijOl 

Expeditionary  Forces,  immediately  on  arrival  in  France.    The  fol- 
lowing report  was  made : 

1.  As  per  instructions,  I  have  made  a  study  of  tlie  above  subject  from 
November  2S  to  the  present  date. 

2.  The  Siebe-Gorman,  Dreyer,  and  Garsaux  oxygen  apparatuses  have  been 
studied  during  this  period. 

3.  A  visit  of  two  weeks  and  a  Iialf  to  Advance  Headquarters,  Royal  Flying 
Corps,  British  Expeditionary  Forces,  gave  oppcytimity  to  interview  practically 
all  the  surgeons,  experts,  squadron  commanders,  supply  officers,  and  others 
acquainted  with  the  "  oxygen  situation."  From  a  practical  standpoint,  it  is 
now  definitely  determine<i  that  oxygen  must  be  supplied  to  those  flying  above 
15,000  feet. 

4.  The  great  heights  now  attained  make  it  essential  that  some  type  of  oxygen 
apparatus  be  produced  at  once  for  our  Service. 

5.  From  my  observations,  it  appears  that  the  Dreyer  apparatus  is  the  best 
of  those  now  in  use.  This  apparatus  has  been  used  in  active  service  at  the 
British  front  for  over  eight  months  and  found  satisfactory.  On  the  date  of 
December  1,  1917,  there  were  from  40  to  50  in  actual  daily  use.  The  Command- 
ing General  stated  that  the  only  reason  these  apparatuses  were  not  used  in 
larger  numbers  was  they  could  not  be  supplied  fast  enough. 

6.  I  recommend  that  the  Dreyer  apparatus  be  adopted  by  the  Air  Service, 
United  States  Army,  and  that  they  be  manufactured  in  large  quantities  at 
once  in  the  United  States.  Also  recommend  that  this  apparatus  be  manu- 
factured in  the  United  States  to  supply  the  Royal  Flying  Coi"ps;  this  would 
be  appreciated  by  them. 

7.  Further  refinements,  alterations  or  improvements  that  may  be  possible 
can  be  undertaken  by  our  Research  Board  in  the  States,  in  connection  with 
Lieut  Col.  Dreyer,  who  will  shortly  work  with  them  in  an  advisory  capacity 
in  Washington,  D.  C.  It  seems  best,  at  present,  however,  to  rush  through  the 
production  of  the  present  Dreyer  apparatus  for  immediate  use. 

The  Air  Service,  American  Expeditionary  Forces,  by  cable  to  the 
United  States,  ordered  the  production  of  approximately  $700,000 
worth  of  Dreyer  oxygen  apparatus.  (On  arrival  in  the  United 
States  we  find  that  this  is  in  production.) 

Visits  to  squadrons  at  the  British  front  brought  out  the  following 
information : 

INTERVIEWS    WaTH    COMMANDING    OFFICERS,    FLIERS,    AND    OBSERVERS    AT 

THE  BRITISH  FRONT. 

BEGAKDING  VALUE  OF  THE  TJSE  OF  OXYGEN   FOE  FLIEES. 

Maj.  D^ ,  commanding  officer,  Squadron,  Royal  Flying 

Corps : 

We  advise  our  men  to  fix  the  mask  in  position  before  leaving  the  ground. 
When  using  the  Dreyer  apparatus  at  an  altitude  of  over  10,000  feet  it  is  best 
for  the  pilot  to  adjust  the  mask  and  wear  it  from  the  time  he  starts  until  he 
comes  back  and  gets  out  of  the  plane.  There  is  no  question  that  these  men 
in  my  command  who  have  used  the  oxygen  apparatus  are  not  by  any  means 
as  tired  as  they  used  to  be  before  they  used  this  apparatus.    The  symptoms 


102  AIR  SEEVICE  MEDICAL. 

«  «  <    • 

complained  of  occurred  usually  after  a  flight  of  an  altitude  of  over  15,000  or 
16,000  feet.     Following  are  tlie  main  symptoms: 

Headache. — Tliis  is  usually  the  first  symptom  noted. 

Fatigue. — As  a  rule  this  is  so  marked  that  the  flier  on  returning  to  his 
squadron  is  almost  too  tired  to  appear  before  me  and  make  a  report  of  his 
flight. 

.  Vertigo. — One  man  first  noticed  that  he  was  dizzy,  and  then  at  an  altitude 
of  18,000  feet  he  fainted.  This  occurred  at  a  position  20  miles  over  the  fighting 
line,  within  the  enemy  territory.  After  the  plane  had  dropped  for  a  con- 
siderable distance  this  man  regained  consciousness  and  came  back  safely  to 
his  squadron,  a  distance  of  over  30  miles.  He  made  a  good  landing,  but  then 
immediately  fainted.     Vertigo  has  been  complained  of  frequently. 

Since  the  use  of  the  oxygen  the  men  have  not  complained  of  any  headache, 
fatigue  (except  what  you  might  call  ordinary  fatigue),  or  vertigo. 

Maj.  D commands  a  squadron  of  high  fliers  exclusively,  and 

they  have  been  using  the  Dreyer  oxygen  apparatus  for  several 
months. 

Capt.  P ,  pilot,  who  has  been  flying  at  an  average  height  of 

20,000  feet: 

Before  the  oxygen  apparatus  was  used  I  used  to  suffer  a  great  deal  from 
flying  at  high  altitude.  I  would  notice  a  palpitation  of  my  heart  not  only  In 
the  air  at  this  high  altitude,  but  also  on  the  ground  for  a  period  of  24  hours 
after  a  flight.  I  would  have  a  bad  headache,  not  only  in  the  air,  but  also 
after  coming  down.  This  would  last  from  5  to  6  hours.  I  used  to  get  this 
palpitation  of  the  heart  and  headache  when  I  would  fly  over  16,000  feet;  I 
would  also  feel  "  rotten  and  done  up,"  and  as  time  went  on  it  became  so  bad, 
I  was  so  tired  I  could  not  sleep  for  30  hours;  if  I  would  fly  on  Monday  I 
would  be  unable  to  sleep  Monday  afternoon,  Monday  niglit,  or  all  day  Tuesday, 
and  I  would  have  my  first  sleep  on  Tuesday  night.  I  do  not  know  how  to 
explain  why  I  could  not  sleep ;  it  was  apparently  not  in  any  way  due  to 
"  nervousness." 

Since  I  have  used  the  oxygen  apparatus  I  have  had  no  palpitation,  no  head- 
ache, no  fatigue  at  all,  and  I  sleep  normally. 

An  observer.  This  man  says  that  he  has  been  flying  at  an  average 
height  of  20,000  feet  for  several  weeks,  and  that  he  is  very  active  in 
tlie  use  of  the  machine  gun  and  he  has  not  had  any  symptoms  at  all. 
He  does  not  feel  that  he  would  have  any  need  of  oxygen  whatever; 
he  states  also  that  it  would  be  a  great  nuisance  for  an  observer  to 
have  to  wear  a  mask,  because  it  would  interfere  with  his  movements 
in  the  rear  compartment. 

An  observer.  This  man  had  seen  active  service  at  high  altitudes, 
and,  as  in  the  previous  report,  he  did  not  notice  any  discomfort,  or 
any  impairment  of  his  mental  or  physical  efficiency.  However,  after 
seeing  active  service  of  six  months  he  states  he  has  "  vertigo  and 
fatigue,"  and  after  he  has  come  down  from  a  great  height  he  now 
feels  "  done  up." 

COMMENT. 

From  a  medical  standpoint  it  is  definitely  determined  that  no 
himian  being  can  fly  at  altitudes  such  as  20,000  feet  for  any  consid- 


AIR  SEEVICE  MEDICAL.  103 

erable  length  of  time  -withont  doing  himself  a  definite  injury.  This 
eli'cct  of  "  OXYGEN  WANT  "  is  most  marked  on  the  central  nervous 
system.  The  writer  was  present  for  one  week  at  the  examinations 
made  upon  fliers,  all  of  whom  were  suffering  from  the  effects  of  high 
flying.  In  the  Twenty-fourth  General  Hospital,  British  Expedition- 
ary Forces,  one  ward  is  devoted  to  the  care  of  fliers  suffering  from 
"OXYGEN  WANT,"  and  during  the  week  mentioned  there  were 
observed  22  such  cases.  The  entire  group  of  men,  from  all  appear- 
ances, looked  perfectly  healthy.  Here  was  a  ward  full  of  young 
active  men  suffering  in  no  way,  and  they  could  have  been  used  in 
any  other  service,  but  not  one  of  these  men  was  able  to  continue  with 
his  duties  as  a  flier. 

These  men  were  examined  by  Capt.  Dudley  Corbett,  Eoyal  Army 
Medical  Corps,  who  made  a  special  point  of  the  following  tests: 

THE  "  FI,ACK  "  OXYGEN  TEST. 

The  Flack  apparatus  consists  of  a  bag  containing  5  liters  of  air 
taken  from  the  room  in  which  the  examination  was  made;  attached 
to  this  bag  is  a  tin  cylinder  which  contains  chemicals  which  would 
take  up  any  carbon  dioxide  that  passed  through  the  can;  there  is  a 
mouthpiece  at  the  other  end  of  the  can.  First  of  all,  the  air  from 
the  room  would  be  forced  in  the  5-liter  bag,  then  the  man  to  be  ex- 
amined would  take  the  mouthpiece  into  his  mouth  and  close  his  lips 
firmly  upon  it ;  he  would  then  breathe  in  and  out  through  his  mouth, 
holding  his  nose  all  the  time.  The  only  air  which  he  was  obtaining 
came  from  the  5-liter  bag ;  the  carbon  dioxide  which  he  would  exhale 
was  absorbed  by  the  chemicals  in  the  tin  box,  so  that  he  was  able  to 
keep  on  breathing  this  air  until  the  amount  of  oxygen  in  the  bag 
became  so  small  that  he  was  not  able  to  stand  it  any  longer.  The 
length  of  time  that  the  man  was  able  to  keep  this  up  was  noted ;  then 
a  sample  of  the  air  in  the  bag  was  taken  and  immediately  examined, 
and  the  percentage  of  the  oxygen  in  the  bag  was  determined  by  care- 
ful analysis;  and  in  this  way  it  was  very  simple  to  determine  what 
altitude  this  man  would  be  able  to  attain. 

THE  CONDITION  OF  THE  NERVOUS  MECHANISM  OF  THE  HEART. 

The  pulse  was  taken,  counting  each  quarter  of  the  minute  for  one 
minute  with  the  man  seated  at  rest.  This  was  repeated  with  the  man 
standing  up,  and  again  repeated  after  the  man  had  stepped  up  and 
down  upon  a  chair  five  times;  he  placed  his  right  foot  on  the  chair 
and  stepped  up  on  the  chair,  bringing  his  left  foot  up  to  the  chair, 
and  repeating  this  exercise  five  times.  This  simple  test  was  very 
helpful  in  determining  whether  slight  exercise  would  cause  a  marked 
increase  of  the  pulse  rate. 

It  is  definitely  determined  that  the  aviator  who  flies  above  10,000 
feet  MUST  HAVE  OXYGEN.  Its  routine  use  would  prove  very 
valuable,  not  only  in  keeping  up  the  efficiency  of  the  aviator,  but  in 


104  AIR  SERVICE  MEDICAL. 

prolonging  the  period  of  time  of  his  service  before  it  would  be  neces- 
sary to  send  him  away  for  a  rest. 

Nothing  could  better  illustrate  that  the  medical  problem  of  avia- 
tion is  a  special  problem  than  a  study  of  these  pilots  at  the  Twenty- 
fourth  General  Hospital.  Not  a  single  man  was  injured  in  body  or 
limb,  and  according  to  usual  medical  standards  and  usual  methods 
of  examination  each  one  of  these  men  would  be  considered  as  per- 
fectly fit  for  service.  As  a  matter  of  fact,  not  a  single  man  was  fit 
for  service.  They  were  unable  to  fly.  Their  chief  complaints  on 
attempting  to  fly  were  headache,  vertigo,  and  "  lack  of  confidence." 
It  seems  to  me  that  there  are  two  possible  causes  for  this  undermining 
of  the  stability  of  the  central  nervous  system : 

1.  The  cumulative  effect  on  the  nervous  system  of- an  insuf- 

ficient supply  of  OXYGEN. 

2.  The  unquastioned  factor  of  the  "  MENTAL  STEAIN  "  of 

long-continued  service. 
Maj.  James  L.  Birley  and  Capt.  Dudley  Corbett,  in  charge  of  the 
British  work  at  the  front,  have  asked  for  our  American  turning-chair 
in  order  to  have  another  method  of  testing  the  stability  or  instability 
of  the  central  nervous  sj^stem.  Just  as  the  heart  shows  marked 
rapidity  because  of  lack  of  tone  of  its  nerve  mechanism,  so  stimula- 
tion of  the  ear  would  produce  hyperactive  responses;  no  flier,  for 
example,  should  be  returned  to  active  service  who  is  quickly  nauseated 
after  a  few  turns  in  the  chair.  They  therefore  plan  the  following 
tests  in  routine  study  of  this  type  of  cases : 

1.  The  Flack  oxygen  test. 

A.  Noting  the  length  of  time  that  the  individual  is  able 

to  continue  his  rebreathing  before  becoming  faint 
or  dizzy. 

B.  An  analysis  of  the  percentage  of  oxygen  in  the 

5-liter  bag. 

C.  A  careful  estimate  of  the  quality  and  rapidity  of 

the  pulse  during  the  time  that  the  individual  is 
breathing  in  and  out  of  the  Flack  bag. 

2.  The  examination  of  the  pulse  before  and  after  graded  ex- 

ercises. 

3.  The  turning  test,  in  the  turning-chair,  to  determine  the  sta- 

bility of  the  ear  mechanism,  including  the  internal  ears 
and  the  intracranial  pathways  from  the  ears. 
By  means  of  these  tests,  the  examiner  is  able  to  give  an  intelligent 
opinion  as  to  the  disposition  of  the  pilot;  he  thus  can  recommend 
that  he  should  be  sent  to  his  home  in  England  on  a  vacation,  or  be 
sent  to  England  to  one  of  the  training  schools  to  act  as  instructor  to 
cadets,  or  kept  in  the  hospital  for  a  short  time  for  observation,  or  be 
sent  at  once  to  the  front. 


AIE  SEEVIOE  MEDICAL.  105 

Maj.  James  L.  Birley,  Royal  Army  Medical  Corps,  Maj.  G.  Dreyer, 
Royal  Army  Medical  Corps,  and  Capt.  Dudley  Corbett,  Royal  Army 
Medical  Corps,  are  responsible  for  the  development  of  all  this  work 
at  the  British  Front.  The  idea  originated  with  Maj.  Birley,  and  he 
has  by  his  own  personal  initiative  created  this  special  service.  The 
fliers  who  are  incapacitated  for  one  reason  or  another  are  sent  to 
Maj.  Birley  and  Capt.  Corbett  for  study.  After  such  study  they 
make  recommendations  as  to  the  disposition  of  each  individual  pilot 
or  observer. 

The  following  was  written  by  Maj.  James  L.  Birley,  Royal  Army 
Medical  Corps,  for  our  information : 

GENERAL   ADMINISTRATION    MEDICAL   SERVICES   ATTACHED    TO    ROYAL    FLYING 

CORPS. 

All  medical  officers  attached  to  the  Royal  Flying  Corps  hold  commissions  in 
the  Royal  Army  Medical  Corps  and  come  under  the  general  administration  of 
the  Army  Medical  Service,  both  at  home  and  in  the  field. 

AU  medical  officers  attached  to  the  flying  services  act  in  an  advisory  capacity 
only.  For  example,  there  is  a  Medical  Research  Committee  sitting  in  London 
which  advises  the  heads  of  department  of  the  flying  services  direct,  and  does 
not  act  through  the  administrative  head  of  the  Medical  Department  of  the  Air 
Service,  as  with  us  no  such  administrative  head  exists  in  the  field.  I  really 
correspond  to  the  Medical  Research  Committee  at  home,  and  give  my  advice  to 
the  General  Officer  Commanding  in  the  Field  direct. 

As  regards  administrative  authority  I  act  through  the  Director  General 
Medical  Service  in  France,  but  I  am  allowed  considerable  freedom  in  this 
respect  as  a  matter  of  courtesy. 

The  Flying  Corps  In  the  Field  is  organized  as  follows : 

Brigades. 

, I ^ 

I  I  I 

Corps  (Artillery)  Wing,  Army  Wing,  Balloon  Wing, 

3  to  6  squadrons.  3  to  12  squadrons.  4  to  14  balloon  sections. 

Each  squadron  consists  of  18  to  21  machines.  There  is  one  Brigade  to  each 
Army,  and  in  addition  there  are  two  Wings  not  attached  to  Armies,  which  come 
under  the  direct  orders  as  regards  operations  of  the  General  Officer  Command- 
ing, Royal  Flying  Corps. 

One  medical  officer  is  attached  to  each  Brigade  and  in  a  few  cases  to  each 
Wing,  excluding  the  Balloon  Wing. 

He  is  responsible  to  the  Director  Medical  Services  of  his  Army  for  sanitation, 
etc.  His  special  duty  is  to  study  the  flying  man,  and  in  this  respect  he  is 
guided  by  me.  Acting  under  the  authority  of  the  Director  General  Medical 
Services,  I  give  orders  to  the  Brigade  and  Wing  medical  officers  for  the  disposal 
of  all  flying  officers  who  are  suffering  from  any  of  the  special  disorders  of 
flying,  such  as  to  render  them  unfit  for  active  service  flying.  Within  limits  no 
flying  officer  Is  allowed  to  go  sick  to  hospital  without  first  being  seen  by  his 
Brigade  or  Wing  medical  officers. 

The  Brigade  medical  officers  are  supplied  with  a  little  special  equipment 
(sphygmomanometer,  aural  specula,  eustachian  catheter,  etc.). 

He  is  responsible  for  seeing  that  the  medical  orderly  attached  to  each 
squadron  is  capable  of  dealing  with  any  ordinary  emergency. 


106  AIR  SEBVICE  MEDICAL. 

The  morning  sick  of  squadrons  and  balloons  are  dealt  with  by  neighboring 
medical  units. 

,     Ordinary  medical  equipment  is  supplied  through  the  Director  Medical  Service 
of  the  Army  concerned,  such  as  drugs,  di-essings,  splints,  etc. 

I  am  trying  to  get  one  medical  officer  per  Wing  recognized  as  the  proper 
establishment,  but  at  present  suitable  medical  officers  are  scarce.  With  only 
one  medical  officer  per  Brigade,  it  is  quite  impossible  for  him  to  get  to  linow 
personally  all  the  flying  officers  in  his  Brigade,  and  Uiis  constitutes  a  serious 
disadvantage. 

Since  the  beginning  of  October  a  ward  at  Twenty-fourth  General  Hospital,  at 
,  has  been  put  at  the  disposal  of  the  Royal  Flying  Corps  for  the  recep- 
tion of  cases  suffering  from  the  special  disorders  of  flying.  Officers  are  sent 
down  there  with  a  Field  Medical  Card,  filled  in  by  the  Brigade  medical  officers, 
and  the  beds  are  very  ably  looked  after  by  Capt.  Dudley  Corbett,  M.  D. 

MAIN  PEINCrPLKS  GOVEENING  THE  MEDICAL  SEKVICE  ATTACHED  TO  THE  EOYAL  FLTINO 
COEP8,  AND  METHODS  BY  WHICH  WE  TBY  TO  CAKBY  THEM  OUT. 

1.  Systematic'  metllcal  examination  of  all  candidates  for  flying  officers, 

2.  Medical  history  of  every  flying  officer  from  the  day  he  joins,  compiled  by 
metlical  officers  attached  to  the  Royal  Flying  Corps. 

3.  Selection  of  candidates  for  particular  tj^es  of  work. 

4.  The  care  of  flying  officers  in  the  air  and  on  the  ground. 

5.  Scientific  research. 

Of  these  (1)   is  being  systematically  carried  out  at  home. 

(2)  This  is  being  partially  done  by  sending  all  flying  officers  sufifering  from 
the  special  disorders  of  flying  to  the  special  ward  at  Twenty-fourth  General 
Hospital.  From  here,  if  they  are  temiwrarily  unfit  for  service  flying,  they  j^re 
evacuated  to  the  Central  Royal  Flying  Corps  Hospital,  in  England.  A  record 
in  duplicate  is  kept  of  every  officer  admitted  to  the  Twenty-fourth  Gleneral  Hos- 
pital, and  one  copy  goes  with  him  to  England. 

Every  candidate's  medical  state  is  filed  at  home  and  can  be  referred  to  by  me 
when  occasion  arises. 

Ordinary  sick  and  wounded  are  sent  to  the  nearest  miltary  hospital.  Those 
who  have  to  be  evacuated  to  England  are  sent  to  the  Central  Royal  Flying 
Corps  Hospital,  and  are  never  seen  by  me.  If  not  sent  to  England,  they  are 
either  returned  (slight  cases)  direct  from  the  field  hosptal  to  their  squadrons; 
otherwise  they  are  treated  at  the  base  and  then  returned  to  one  of  our  two 
base  depots.  Here  they  report  to  the  medical  officer  In  charge  of  the  depot,  and 
If  marked  "  Fit "  are  posted  to  squadrons.  If  temporarily  unfit,  I  am  Informed, 
It  is  arranged  to  have  them  sent  to  Twenty-fourth  General  Hospital  for  over- 
haul. 

The  arrangement  of  having  flying  men  sent  to  our  special  ward  at  Twenty- 
fourth  General  Hospital,  who  are  suffering  from  conditions  the  direct  result  of, 
or  of  particular  importance  as  regards  flying,  and  having  ordinary  sick  and 
wounded  on  the  other  hand  dealt  with  by  the  ordinary  field  and  base  hospitals, 
answers  well,  provided  that  cases  returned  from  hospital  in  France  are  passed 
fit  for  flying  before  being  posted,  by  a  medical  officer  attached  to  the  Royal 
Flying  Corps;  and  (b)  those  who  have  to  be  sent  to  England  are  treated  at 
the  Central  Hospital,  where  flying  is  specially  understood.  Both  these  pro-, 
visos  are  in  course  of  fulfillment.  In  the  case  of  (a),  if  there  is  any  doubt  as 
to  a  man's  fitness,  he  is  sent  to  the  si^ecial  ward  at  Twenty-fourth  General  Hos- 
pital for  investigation.  From  there  we  can  send  a  man  to  England  on  three 
weeks'  sick  leave  when  occasion  seems  to  demand  it 

(3)  This  Is  being  done  at  home,  but  to  what  extent  I  do  not  know. 


Ant  SEBVTCE  MEDICAL.  107 

(4)  In  France,  I  act  ns  adrlsor  In  respect  to  clothing,  protection  agalnist 
frostbite,  oxygen,  the  perlofls  of  service  and  rest,  etc. 

Royal  Flying  Corps  squadrons  have  a  special  nllotment  of  leave  which  gives 
them  14  days  In  Englnnd  about  every  three  months.  Pilots  and  observers  gen- 
erally go  home  (to  rest,  to  act  as  instructors  In  the  air,  on  the  ground,  etc.) 
after  five  or  six  months  in  fighting,  long  reconaissnnces  and  bombing  squad- 
rons, and  after  seven  to  nine  months  In  artillery  squadrons.  It  is  Impossible, 
and  I  think  it  would  be  very  unwise  to  try,  to  lay  down  a  law  for  everyone, 
not  only  because  individuals  vary,  but  also  on  account  of  the  varying  number 
o/  hours  flown  per  month  according  to  the  state  of  the  weather,  activity  on  the 
front,  etc.  A  good  artillery  pilot  will  get  through,  in  rough  figures,  350  to 
450  hours,  before  he  goes  home;  a  good  scout  pilot  150  to  250  or  300  hours. 
As  a  general  rule,  not  more  than  two  "  shows  "  over  the  lines  are  done  by  any 
one  flying  man  per  day.  This  in  an  artillery  squadron  would  mean  seven  hours 
flying,  in  a  single-seater  fighter  four  hours,  and  in  a  two-seater  fighter  five 
hours,  per  day.  Pilots  doing  long  reconnaissance  work,  or  long  bomb  raids, 
are  very  rarely  called  upon  to  do  more  than  one  flight  a  day,  I.  e.,  three  to  four 
hours;  but  with  oxygen  two  flights  can  be  and  have  been  done,  without  ill 
effects. 

It  win  thus  be  seen  that  our  flying  personnel  Is  kept  at  it  pretty  hard. 
Casualties  are  always  replaced  within  a  few  hours,  and  each  squadron  has  an 
excess  of  two  pilots  over  the  number  of  machines. 

It  Is  one  of  the  prime  duties  of  a  squadron  commander  to  look  out  for  tired 
pilots,  and  In  this  he  is  helped  by  the  Brigade  medical  oflicer.  The  latter  can 
always  refer  any  case  direct  to  the  oflicer  commanding  the  Brigade. 

No  medical  officer  can  order  a  pilot  to  go  home  for  a  rest,  but  merely 
advises  his  brigadier,  and  things  being  as  they  are,  I  should  be  very  sorry  to 
have  this  practice  changed.  Such  cases  are  frequently  referred  to  me  for 
decision,  and  I  always  make  a  point  of  consulting  the  squadron  commander  of 
the  oflicer  under  dtecussion. 

A  Brigade  medical  officer  can  order  any  flying  officer  to  hospital,  and  if  he  is 
suffering  fi-om  fatigue,  etc.,  he  automatically  goes  to  Twenty-fourth  General 
Hospital,  at  once,  where  all  such  cases  are  seen  by  me.  Until  compara- 
tively recently,  it  has  been  the  practice  to  send  tired  pilots  to  England  to  the 
Home  establishment  without  any  medical  supervision.  I  do  not  think  this 
is  sound,  and  we  are  now  having  increasing  numbers  of  tired  men  sent  to 
T\venty-fourth  General  Hospital,  where  we  can  give  them  a  preliminary  rest 
and  overhaul,  and  form  some  idea  of  their  fitnef".s  for  the  future. 

As  regards  the  health  of  flying  oflJicers  in  aerodromes,  exercise  Is  Insisted 
on  in  the  winter  but  not  In  the  summer.  No  rules  exist  about  tobacco  or 
alcohol.  There  is  no  serious  abuse  of  the  latter,  but  the  majority  of  pilots 
undoubtedly  smoke  far  too  much. 

I  am  arranging  lectures  during  the  winter  on  •'  health,"  and  shall  talk  about 
venereal  disease.  There  Is  too  much  of  this  In  the  Flying  Corps,  but  the 
trouble  is  that  90  per  cent  of  it  is  caught  on  leave  in  England  or  in  base  ports 
when  coming  out  to  Franae.  The  General  Officer  Commanding  has  empowered 
us  to  do  what  I  think  best  in  this  matter, 

POOLS. 

At  each  of  our  base  depots  is  a  pool  of  flying  officers,  where  new  pilots  from 
England,  and  others  discharged  from  hospital,  await  their  turn  to  be  posted,  to 
fill  up  casualties. 

These  pools  are  not  satisfactory,  as  it  Is  impossible  to  provide  suitable  em- 
ployment on  the  ground  for  any  group  of  people  whose  prime  duty  Is  In  the 


108  AIE  SERVICE  MEDICAL. 

air,  and  whose  numbers  vary  from  day  to  day  (e.  g.  from  over  100  to  15).  A 
new  and  Inexperienced  pilot  from  England  who  has  to  wait  10  days  or  a 
fortnight  at  the  pool  before  being  posted,  and  has  probably  absorbed  in  that 
time  a  good  deal  of  morbid  "  shop,"  arrives  at  his  new  squadron  with  his  tail 
down.  The  whole  question  has  been  talfen  up,  and  the  practicability  of  turning 
the  pools  into  schools  of  gunnery  instruction  on  the  ground  is  being  considered 
as  a  satisfactory  solution, 

INEFFICIENT  PILOTS   AND   OBSERVEES.  ' 

Our  general  policy  as  regards  these  is  as  follows : 

Officers  found  permanently  unfit  for  further  flying  on  medical  grounds,  but 
fit  for  general  service  in  the  infantry  or  artillery,  etc.,  are  disposed  of  by  the 
Personnel  Branch  at  Headquarters,  Royal  Flying  Corps.  If  an  officer  has 
done  well  as  a  flying  officer,  every  effort  is  made  to  retain  him  in  the  Flying 
Corps  on  a  ground  job.  If  he  has  only  been  flying  a  short  time  and  seems 
likely  never  to  make  an  aviator,  he  is  transferred  to  some  other  branch  of  the 
service. 

An  officer  who  is  "  technically  "  inefficient  is  not  dealt  with  by  the  Medical 
Service.  Those  who  are  "  temperamentally "  unfit  are  generally  referred  by 
the  Personnel  Branch  to  me  in  order  that  they  may  have  my  views  before 
making  a  decision. 

Experience  has  taught  me  to  group  cases  of  loss  of  nerve  in  the  air  as 
follows : 

(a)  Loss  of  nerve  for  flying  any  machine — as  far  as  my  experience  goes, 
this  condition  is  nearly  always  permanent. 

(&)  Loss  of  nerve  for  "stunting" — this  is  usually  temporary,  and  associated 
very  often  with  symptoms  of  vertigo,  etc. ;  of  recent  origin.  In  some  cases, 
however,  it  has  been  present  from  the  start  and  has  been  thoroughly  sup- 
pressed. I  intend  recommending  such  cases  as  pilots  on  heavy  and  stable 
bombing  machines;  for  example,  the  Handley-Page. 

(c)  Loss  of  nerve  for  fighting  in  the  air — this  may  be  temporary  or  perma- 
nent, according  to  the  degree  of  fatigue. 

(d)  Loss  of  nerve  for  anti-aircraft  shells — this  seems  to  be  more  generally 
permanent  than  otherwise.  An  officer  who  has  been  blown  up  by  a  shell  or 
bomb  on  the  ground  and  has  had  physical  or  mental  manifestations  as  an  im- 
mediate result  (so-called  "shell  shock"),  is  in  my  opinion  almost  invariably 
mentally  incapable  of  facing  anti-aircraft  fire. 

(e)  Loss  of  nerve  due  to  crashes — in  a  very  large  majority  there  is  a  his- 
tory of  concussion  at  the  time  of  the  crash,  and  I  never  commit  myself  to  an 
optimistic  prognosis  in  these  cases.  The  presence  of  fatigue  is  very  often 
associated  in  the  case  of  a  good  pilot  with  some  change  in  his  behavior  in  the 
air,  etc. 

The  most  frequent  symptom  is  stunting  near  the  ground.  Pilots  have  often 
told  me  that  they  do  this  to  try  and  convince  themselves  that  they  are  as  con- 
fident as  ever. 

I  do  not  think  it  is  necessary  for  me  to  refer  to  symptoms,  such  as  un- 
sociability, loss  of  weight,  lack  of  physical  and  mental  energy,  bad  dreams, 
insomnia,  low  blood  pressure  with  an  increase  above  the  normal  of  the  pulse 
pressure,  as  you  have  seen  all  these  cases  at  Twenty-fourth  General  Hospital. 

WOEK   AT   TWENTY-FOUETH    GENEEAL   HOSPITAL, 

In  addition  to  the  lines  of  investigation  which  you  saw,  we  hope  in  the  near 
future  to  get  written  records  of  pulse,  respiration,  and  blood  pressure  during 
the  test  with  Flack's  bag.    This  will  give  a  clearer  indication  of  how  a  man 


AIR  SERVICE   MEDICAL.  109 

reacts  to  lack  of  oxygen,  and  can  be  obtained,  by  merely  recording  the  per- 
centage of  oxygen  at  which  symptoms  of  syncope  supervene. 

Capt.  Corbett  has  already  bosuii  to  make  nysteuiatic  Haemoglobin  estimations, 
both  at  rest  and  during  the  bag  test.  I  hope  shortly  to  obtain  the  assistance 
of  Capt.  H.  C.  Basett  at  Twenty-fourth  General  Hospital,  as  the  work  is  rapidly 
becoming  too  heavy  for  one  man.  This  officer  is  well  known  to  Dr.  Coile,  as 
he  visited  the  station  when  holding  the  Oxford  Radcliffe  Traveling  Research 
Fellowship,  and  has  for  some  months  been  conducting  researches  on  shock  in 
cases  of  gun-shot  wounds.  » 

I  also  hope  to  see  Mr.  Sydney  Scott  installed  there  shortly  to  undertake  the 
otological  work  on  a  comprehensive  scale.    I  feel  very  strongly  that  we  should 

be  possessed  at of  the  proper  methods  of  investigation  to  enable 

us  to  state  whether  a  man  is  fit  for  service  flying  or  not ;  and,  if  unfit,  whether 
temporarily  or  permanently.  I  do  not  consider  that  we  are  justified  in  embark- 
ing on  any  elaborate  or  theoretical  methods  of  research,  as  it  seems  to  me  that 
this  is  better  done  in  England  and,  I  am  glad  to  be  able  to  add,  America. 

THE  USE  OF   OXYGEN   IN   THE   AIB. 

The  report  written  by  me  on  the  effects  of  high  flying  at  high  altitudes,  dated 
March  27,  1917,  still  holds  good  in  the  main,  and  there  is  no  doubt  that  flying 
above  10,000  feet  is  more  tiring  than  flying  below  that  height. 

Three  D.  H.  4  squadrons  are  now  completely  equipped  with  oxygen  apparatus, 
and  use  it  as  a  routine  in  spite  of  the  extra  weight  entailed  and  various  draw- 
backs with  regard  to  the  present  type  of  mask. 

I  do  not  propose  "  pushing "  oxygen  until  the  improved  masks  and  light 
cylinders  are  in  this  country  in  large  quantities,  as  an  unnecessary  weight  and 
uncomfortable  mask  only  prejudice  pilots  against  oxygen.  In  fact,  the  whole 
question  of  popularizing  oxygen  depends  on  the  recognition  of  the  necessity  of 
providing  the  individual  with  an  apparatus"  which  he  prefers  to  use  than  to  do 
without.  And  in  this  connection  too  much  stress  can  not  be  laid  on  the  mask, 
because  here  we  are  right  up  against  the  individual,  and  the  wide  use  of 
oxygen  resolves  itself  in  the  end  into  the  provision  of  a  comfortable  mask  which 
pilots  will  use. 

It  has  been  found  that  it  is  essential  for  the  observer  to  be  able  to  disconnect 
himself  from  his  regulator,  otherwise  the  tubing  between  mask  and  regulator 
interferes  with  his  movements,  the  mask  is  pulled  off,  and  probably  never 
replaced. 

We,  therefore,  intend  in  future  to  have  a  standard  length  (3  or  4  feet)  of 
tubing  attached  to  the  mask,  both  for  pilot  and  observer.  By  means  of  a  bayonet 
screw  joint  this  is  connected  with  the  tubing  from  the  oxygen  outlet  of  the 
regulator.  When  the  aviator  wishes  to  disconnect,  he  has  only  to  take  hold 
of  the  joint,  give  it  a  half  turn  and  pull ;  he  will  then  be  left  with  a  small  length 
of  tubing  attached  to  his  mask,  not  long  enough  to  get  in  his  way,  and  the  distal 
end  of  the  other  length  of  tiibing  will  be  fixed  to  the  side  of  the  machine  handy 
for  reconnection  when  required.  In  this  way  the  mask  is  retained  on  the  face, 
a  point  of  practical  importance.  For  individuals  who  particularly  dislike  any 
form  of  mask,  the  Flack  rigid  mask  will  be  provided,  hung  up  in  any  con- 
venient position,  and  when  oxygen  is  needed  the  observer  merely  holds  it  over 
his  face. 

Our  aim  is  to  provide  pilot!<,  who  do  not  move  about,  with  a  continuous  supply 
from  the  automatic  Dreyer  regulator,  and  observers  with  an  intermittent  supply, 
either  from  the  same  regulator  or  from  the  Siebe-Gorman  Mark  II,  giving  them 
the  mask  which  they  individually  prefer. 


110 


AIE  8EKVICE  MEDICAL. 


We  shnll  shortly  have  three  masks  available: 

1.  The  Improved  Dreyer. 

3.  The  rJRid  Flack. 

3.  The  combhied  helmet  and  mask  in  which  can  be  incorporated,  where 
necessary,  the  wireless  microphone. 
Pilots  nnd  observers  are  advised  to  put  on  the  mask  before  starting. 
The  following  weights  may  be  useful : 


1.  Scout... 

2.  Two-seater  fighter... 

3.  D.  H.-4 

4.  Long  bomber 


Pilot 

/rilot 

\Obsf>rver. 

/Pilot 

\Observer. 

/Pilot 

\Observer. 


Typo  of  regulator. 


Dreyer  (5  lbs.) 

[•Dreyer  (5  lbs.) 

[Dreyer  (5  lbs.) 

S.G.  Mark  11(1  lbs.) 
S.Q.Mark  II  (4  lbs.) 


Cylinder  with  valve. 


(300  L)  5  lbs 

(500  L)  7  lbs 

(500  L)  7  lbs 

2(f;noLeaf>h)14  1bs. 
2  (500  L  each)  14  lbs. 


Duration  of  supply 
at  2  liters  per  min- 
ute per  person. 


2i  hours. 

f2i  hours. 
[1}  hourj. 
(1  hours. 
[\  hours, 
s  hours. 
4  hours  each. 


England  is  being  asked  to  send  the  following  samples,  addressed  to  general 

secretary,  United  States  Army  Aviation,  119  D  Street,  N.  E.,  Washington,  D.  C. : 

Light   oxygen   cylinder   ^jth   valve   containing  500   liters   filled  at   150 

atmospheres. 
Combined  oxygen  and  telephone  mask  and  helmet 
Improved  Dreyer  mask. 
Black  mask. 
Set  of  connections  for  using  one  Dreyer  regulator,   two  cylinders  and 

two  persons. 
Mark  I  goggles. 

Mark  II  Siebe-Gorman  regulator  with  connections,  including  mask. 
I  am  also  writing  to  Capts.  C.  P.  Heald  and  Martin  Flack  reference  your 
proposed  visit  to  England. 

James  L.  Birley, 
Major,  R.  A.  M.  C.  Headquarters,  Royal  Flying  Corps. 
Deceixbee  20,  1917. 

For  your  information,  we  are  also  including  the  following  article 
written  at  the  Front  by  Maj.  James  L.  Birley  on  March  27,  1917: 

MEMORANDUM  ON  THE  EFFECTS   OF  HIGH  FLYING  UNDER  ACTIVE  SERVICE 

CONDITIONS. 

PEELIMINABY. 

This  report  is  based  on  my  own  observations,  as  well  as  on  the  reports  which 
have  been  furnished  by  medical  officers  attached  to  Brigades. 

It  should  be  clearly  understood  that  in  the  period  covered  by  this  report 
there  has  been  only  a  limited  number  of  squadrons  in  which  routine  work  is 
carried  out  at  heights  as  great  as  13,000  to  14,000  feet,  and  a  still  smaller  num- 
ber at  heights  greater  than  these.  In  no  case  is  work  done  above  18,000  feet, 
and  no  squadron  which  works  systematically  at  or  above  15,000  feet  has  been 
out  longer  than  three  months. 

The  effects  of  high  altitude  vary  enormously  in  different  individuals,  and  no 
symptoms  or  group  of  symptoms  are  universal.  A  minority  of  flying  officers 
profess  a  total  ignorance  of  any  symptoms  whatever,  while  others  experience 
them  only  after  they  have  carried  out  several  flights  at  high  altitudes.  In  this 
connection,  it  must  be  remembered  that  the  necessity  of  attention  to  the  tech- 


AIB  SEBVIOE  MEDICAL.  Ill 

nlcal  and  other  duties  of  a  flight  may  in  itself  suffice  to  divert  an  officer's  notice 
from  physical  symptoms,  unless  the  latter  became  imperative. 

Other  factors  which  make  for  a  lack  of  uniformity  in  the  effects  observed 
are  (1)  meteorological  conditions,  (2)  different  types  of  machines,  and  (3) 
vaiying  states  of  physical  fitness.  These  will  be  referred  to  more  fully  in 
subsequent  sections. 

SYMPTOMS   OF   HIGH   FLYING. 

1.  Relatively  constant. —  (1)  During  the  flighli  (in  order  of  frequency)  : 

(a)  Shortage  of  breath  (dyspnoes)  :  This  is  extremely  common,  but  it  varies 
in  degree.  Very  few  pilots  breathe  through  the  nose  above  12,000  feet.  When 
dyspnoes  is  experienced,  its  intensity  varies  directly  with  the  altitude.  It  is 
usually  noticed  at  about  15,000  feet,  and  the  character  of  the  breathing  is 
generally  described  as  "  gasping  "  or  "  panting."  It  is  exaggerated  by  muscxilar 
exertion,  such  as  using  the  pressure  pump,  and  is  more  noticeable  in  cold 
weather  and  cold  machines  than  in  warm.  Pilots  look  upon  this  shortness  of 
breath  as  something  very  ordinary,  and  are  not  in  the  least  alarmed  by  it. 

N.  B.- — It  is  interesting  to  note  that  the  Sopwith  scout,  which  is  an  admittedly 
warm  machine,  has  done  more  high  flying  in  France  than  any  other  one  type. 
The  officer  in  command  of  a  Sopwith  Squadron,  which  has  been  working  at 
15,000  to  16,000  feet  for  three  months,  categorically  denies  that  his  pilots  suffer 
any  inconvenience  from  high  flying  (vide  infra,  however). 

(ft)  Aural  symptoms — tinnitus,  deafness,  giddiness:  These  occur  with  any 
rapid  change  of  altitude,  but  they  are  exaggerated  among  high-flying  pilots. 
Slow  descent  ameliorates  but  does  not  entirely  abolish  the  condition. 

(c)  Paraesthesis — chiefly  of  the  extremities ;  e.  g.,  the  hands,  feel  "  like  cotton 
wool  and  all  numb."  Sometimes  there  is  a  sensation  "  as  if  the  whole  body 
were  swelling." 

(2)  After   landing: 

Fatigue:  This  is  the  commonest  of  all  symptoms.  It  should  be  noted  that  a 
long  flight  at  any  altitude  is  apt  to  be  associated  with  after-fatigue,  and  that 
machines  which  fly  high  are,  generally  speaking,  longer  in  the  air  than  those 
which  fly  low.  Nevertheless,  it  is  quite  certainly  the  case  that  flying  at  heights 
over  11,000  to  12,000  feet  accentuates  the  condition,  and  that  the  greater  the 
height  the  more  lasting  is  the  sense  of  tiredness.  Less  often  it  is  felt  in  the 
air,  as  a  general  feeling  of  loss  of  energy  and  strength.  On  landing  there  is  a 
sense  of  lassitude  and  sleepiness,  and  some  pilots  make  a  point  of  lying  down 
and  going  to  sleep.  The  opinion  is  generally  held  amongst  flying  officers  that  this 
fatigue  is  temporary  and  has  no  bad  after  effects. 

2.  Relatively  inconstant. — 

N.  B. — It  is  difficult  to  group  these  symptoms  in  order  of  frequency,  but  an 
attempt  has  been  made. 

(1)  During  the  flight : 

(a)  Faintness  and  dizziness:  It  is  not  always  possible  to  attribute  these 
conditions  to  altitude.  A  feeling  of  faintness  has  occurred  in  a  few  cases  at  and 
above  17,000  feet ;  several  pilots  at  lower  altitudes  have  "  queer  "  feelings  and 
dizziness. 

The  following  cases  are  of  interest : 

An  N.  C.  O.  pilot  had  been  flying  at  home  up  to  8,000  feet  without  experienc- 
ing any  symptoms  whatever.  One  day,  in  France,  he  reached  12,000  feet  and 
at  once  felt  faint,  sick,  and  breathless.  He  managed  to  descend,  and  at  5,0(K) 
feet  recovered  completely.  On  landing,  he  suffered  from  pains  in  the  head 
which  lasted  an  hour  or  two.  On  examination,  the  apex  beat  was  internal  to 
the  nipple  line,  and  the  area  of  cardiac  dullness  not  increased.  The  pulse  rate 
89118—19 8 


112  AIB  SERVICE  MEDICAL. 

was  100,  and  was  easily  raised  by  slight  exertion,  and  there  was  a  faint  spical 
systolic  murmur,  not  conducted. 

An  officer  extremely  fond  of  flying,  during  the  cold  weather,  suddenly  felt 
faint  and  giddy  one  day  at  10,000  feet.  The  machine  was  landed  by  the  ob- 
server. The  pilot  had  to  be  assisted  out  of  the  machine  and  then  slept  for  a 
long  time,  to  wake  up  with  a  splitting  headache.  Physical  examination  re- 
vealed nothing,  and  his  physique  was  well  above  the  average.  Not  long  after 
this,  in  warmer  weather,  he  fainted  at  12,000  feet.  He  had  never  noticed  short- 
ness of  breath  in  the  air.     This  officer  is  now  doing  well  in  a  Corps  Squadron. 

Two  other  pilots,  both  of  poor  physique  and  slight  build,  feel  faint  and  dizzy, 
one  at  9,000  feet ;  the  other  at  12,000  feet.  The  former  has  cardiac  irritability, 
and  has  already  been  sent  home  to  be  boarded. 

(6)  Nausea  and  vomiting:  This  is  rare  below  15,000  feet,  but  has  occurred 
in  several  officers  above  this  height.  Most  R.  N.  A.  S.  pilots  think  that  the 
exhaust  fumes  are  largely  responsible. 

(c)  Pains  in  one  or  both  ears:  This  persists  for  a  few  hours.  In  one  case 
this  was  associated  with  labyrinthine  deafness ;  in  the  other  there  was  no  evi- 
dence of  ear  disease,  and  the  condition  was  improved  by  regular  Politzeration 
or  catheterization  of  the  Eustachian  tube. 

(d)  Frontal  headache:  Often  sudden  in  onset  and  lasting  for  a  short  time 
after  landing.     One  pilot  has  it  at  12,000  feet ;  another  at  15,000  feet. 

(e)  Intense  desire  to  micturate  and  parched  mouth:  These  usually  go  to- 
gether and  occur  in  spite  of  the  bladder  being  emptied  just  before  leaving  the 
ground.  On  landing  after  a  high  flight  a  large  quantity  of  urine  is  sometimes 
passed. 

(/)  Physical  fatigue:  During  a  high  flight  "one  requires  to  be  pulling 
oneself  together  continually." 

(g)  Diminished  sense  of  stability:  Several  pilots  do  not  care  to  bank  near 
the  ground  on  descending  from  above  10,000  feet,  as  they  are  not  so  certain 
of  that  sense  of  balance  which  is  an  essential  attribute  of  flying ;  there  is  some 
evidence  which  points  to  a  greater  frequency  of  bad  landings  after  high  flyings 
than  low  ones. 

(2)  After  landing: 

(a)  Frontal  headache. 

(6)  Pain  in  ears. 

(c)  Palpitations  of  brief  duration. 

(d)  Trembling  of  hands. 

SIGNIFICANCE  OF  SYMPTOMS. 

The  symptoms  are  divisible  into  two  groups : 

(1)  Those  depending  on  the  fall  of  oxygen  pressure. 

This  group  comprises  probably  all  the  above  with  the  exception  of  ear 
symptoms,  parsesthesis,  and  in  some  cases  headache. 

Severe  cold  undoubtedly  intensifies  the  dyspnea,  a  fact  which  perhaps  may 
be  partly  explained  by  a  constriction  of  the  alveolar  vessels.  Fatigue  is  also 
increased  by  cold. 

Tremors,  altered  sense  of  stability,  muscular  and  mental  fatigue  must  be 
ascribed  to  deficient  oxygenation,  resulting  in  relative  cerebral  anemia. 

The  dryness  of  mucuous  membranes  and  rapid  filling  of  the  bladder  are 
interesting,  in  view  of  the  supposition  that  oligaemia,  or  diminution  of  the 
blood  volume  at  the  expense  of  the  plasma,  plays  a  prominent  role  in  the 
reaction  of  the  organism  to  sudden  and  gross  changes  in  altitude. 

(2)  Those  depending  on  the  fall  of  atmospheric  pressure. 


AIB  SERVICE  MEDICAL.  113 

The  diminution  of  pressure  on  the  body  surface  has,  so  far  as  I  am  aware, 
received  but  scant  attention.  The  subjective  sensations  in  the  lines  may  be 
reasonably  ascribed  to  this  factor. 

Both  headache  and  aural  symptoms  are  exaggerated  by  catarrhal  conditions 
of  the  nose  and  throat.  In  some  cases  the  former  have  been  very  severe. 
Unilateral  earache  is  not  uncommon;  the  origin  and  prevention  awaits 
discovery, 

REMOTE   EFFECTS   OF   CONTINUED    HIGH    FLYING. 

t 

1.  Physical. —  (c)  Blood:  Five  pilots  who  had  flown  at  or  above  15,000  feet 
for  some  months  and  had  occasionally  reached  18,000  feet,  also  five  pilots 
who  had  averaged  11,000  feet  for  five  months  and  had  repeatedly  been  up  to 
15,000  feet,  together  with  controls  (Maj.  Dreyer  and  myself),  were  examined 
in  January. 

All  12  individuals  showed  a  normal  number  of  red  cells,  hemoglobi  percent- 
age, and  color  index,  except  2  pilots,  who  were  slightly  anemic. 

( 6 )  Emphysema :  A  great  many  high-flying  pilots  present  evidence  of  this 
condition,  as  shown  by  the  percussion  note,  together  with  diminution  or  even 
obliteration  of  the  normal  area  of  cardiac  dullness. 

(c)  Cardio-vascular  system:  In  several  pilots  the  apex  beat  has  been  found 
to  be  in  the  left  nipple  line,  and  in  one  case  one-half  inch  external. 

Several  officers,  including  two  very  experienced  pilots,  have  premature  beats 
at  regular  intervals.  They  are  wholly  unaware  of  this  peculiarity,  and  I 
regard  the  condition  with  equanimity. 

Cardiac  irritability  constitutes  an  absolute  bar  to,  and  is  certainly  aggra- 
vated by,  high  flying.  As  to  whether  this  condition  is  caused  de  novo  by  high 
flying,  it  is  yet  too  early  to  make  a  positive  statement,  but  there  is  evidence 
that  such  is  the  case. 

2.  General. — Vide  under  "  General  conclusions." 

ACCLIMATION. 

Three  pilots  have  definitely  stated  that  this  has  occurred  in  their  own  cases, 
so  that  shortness  of  breath  was  postponed  until  gi'eater  altitudes  were  reached, 
e.  g.,  15,000  feet  instead  of  12,000;  in  two  cases,  18,000  feet  instead  of  15,000 
feet  in  the  other.  All  these  pilots  were  definitely  emphysematous ;  one  has  been 
missing  for  two  months,  and  there  is  reasonable  ground  for  supposing  that  he 
fainted  in  the  air  and  never  recovered  control. 

In  my  opinion,  acclimation  in  the  air  does  not  occur  to  a  sufficient  extent  or 
with  sufficient  rapidity  as  to  render  it  of  any  practical  utility,  and  I  hold  the 
same  view,  though  more  strongly,  with  regard  to  artificial  acclimatization  an 
the  ground. 

GENEBAL   CONCLUSIONS. 

Several  commanding  officers  in  the  field  do  not  anticipate  any  widespread 
physical  disturbances  as  a  result  of  high  flying,  such  as  scientific  knowledge 
would  lead  us  to  expect.  Others,  on  the  other  hand,  fully  realize  the  difficulties 
ahead.  Moreover,  in  one  squadron  in  which  ill  effects  were  stoutly  denied,  two 
officers  have  already  been  seen  whose  condition  is  clearly  attributable  to 
altitude. 

It  should  also  be  noted  that  at  present  no  squadron  flying  at  the  greater 
altitudes  is  working  at  full  pressure;  i.  e.,  there  are  many  "off"  days,  and 
never  more  than  one  flight  in  any  day.  Further,  the  newer  types  of  machines 
are  likely  to  be  faster  climbers,  and  as  far  as  evidence  is  at  present  available, 
rate  of  climb  and  physical  effects  are  directly  related. 


114  AIR  SERVICE  MEDICAL. 

That  an  individual  who  is  tired  or  in  a  poor  state  of  health  is  more  sus- 
ceptible than  one  who  is  fresh  and  fit,  is  a  fact  which  can  be  corroborated 
almost  daily. 

No  exact  data  ai'e  available  for  estimating  the  effects  of  tobacco,  alcohol,  or 
lack  of  exercise,  and  I  feel  this  aspect  of  the  question  is  so  complex  and  so 
intimately  bound  up  with  the  personal  equation,  that  its  treatment  calls  for 
the  greatest  care  and  prudence. 

Finally,  I  believe  one  is  justified  in  concluding  that  flying  at  high  altitudes 

(over  15,000  feet)  entails  additional  strain,  which  will  eventually  result  in  a 

shorter  average  term  of  efficiency  per  pilot;  that  routine  flying  above  18,000 

feet  without  artificial  aid  in  a  large  majority  of  individuals  is  not  a  practical 

proposition ;  and  that  wide  benefits  are  likely  to  accrue  from  the  adoption  of  a 

suitable  oxygen  apparatus. 

James  L.  Bibley, 

Major,  R.  A.  M.  C,  M.  0.  i/c  Headquarters,  R.  F.  G. 

In  the  field,  March  27,  1918. 

We  are  also  including  the  following  article  written  by   Capt. 

Dudley  Corbett,  Eoyal  Army  Medical  Corps,  on  August  3,  1917: 

FLYING  FATIGUE  AND  EFFICIENCY. 

[By  Capt.  Dudley  Corbett,  Royal  Army  Medical  Corps,  attached  to  Royal  Flying  Corps.] 

It  need  hardly  be  re-stated  that  the  essential  aim  of  the  medical  service  of 
any  branch  of  the  Army  is  the  maintenance  of  fighting  efficiency.  These  notes, 
the  result  of  eight  months  experience  with  the  Royal  Flying  Corps  in  the 
Field,  have  been  written  solely  with  this  aim  in  view.  The  various  factors  lead- 
ing to  what  is  here  termed  Flying  Fatigue  are  by  no  means  generally  understood 
by  those  to  whom  such  information  would  be  valuable,  so  that  an  attempt  is 
here  made  to  explain  the  whole  question  in  non-medical  language.  At  the  same 
time  certain  suggestions  are  put  forward  as  ideals  to  be  aimed  at  without 
going  into  details  as  to  whether  they  are  immediately  practicable. 

THE     SELECTION     OF     PEBSONNEL. 

Much  has  already  been  done  toward  the  more  efficient  and  economic  use 
of  personnel,  but  it  is  suggested  that  even  now  there  is  a  considerable  waste 
of  time  and  money  in  training  pilots  who  prove  either  entirely  unsuitable  for 
the  Royal  Flying  Corps  in  any  capacity,  or  at  least  unsuited  for  the  work 
to  which  they  have  been  posted. 

It  seems  that  this  is  to  a  certain  extent  due  to  an  insufficient  appreciation 
of  the  value  of  close  cooperation  between  the  medical  service  and  those  in 
charge  of  personnel,  or,  in  other  words,  that  full  use  is  not  at  present  being 
made  of  scientific  medicine  when  selecting  pilots. 

Given  general  physical  fitness,  it  is  impossible  to  lay  down  any  rules  by 
which  one  may  detect  the  type  of  individual  who  wiU  make  a  first-class  pilot 
under  service  conditions,  unless  one  makes  use  of  special  metliods  of  exami- 
nation. One  finds  first-class  fighting  pilots  among  all  sorts  and  conditions  of 
men,  in  the  thin  weedy  nervous  type  as  well  as  in  the  sturdy  and  robust,  so 
that  it  may  be  safely  said  that  physical  appearance  is  a  fallacious  guide. 

Instead  of  one  Royal  Army  Medical  Corps  officer,  the  candidate  should  be 
examined  by  a  standing  Medical  Board,  one  of  whom  should  possess  previous 
experience  with  the  Royal  Flying  Corps  in  the  Field.  In  order  to  cope  with 
the  work  there  could  be  a  number  of  such  boards  at  given  centers  throughout 
the  country,  such  as  one  for  each  command. 


AIE  SEEVIOE  MEDICAL.  115 

If  the  candidate  is  found  generally  fit,  this  body  should  arrange  for  him  to 
undergo  certain  physiological  tests  to  determine  whether  he  is  likely  to  suffer 
from  dizziness  or  sickness,  and.  further,  to  what  height  he  should  be  able  to 
fly  without  experiencing  symptoms  of  oxygen  starvation.  His  reaction  time 
to  visual,  auditory  tactile  impressions  could  be  taken  in  order  to  test  the 
general  alertness  of  mind  and  body.  Such  tests  have  been  devised  and  are 
being  perfected,  and  their  employment,  though  not  a  necessity,  would  be  of 
great  value.  The  results  of  all  these  investigations  could  be  tabulated,  so  that 
in  the  end  the  authorities  would  possess  information  enabling  them  to  make 
the  best  possible  use  of  the  material  at  their  command. 

Records  of  the  examination  could  be  kept,  so  that  when  at  some  future  date 
the  officer  had  to  go  before  the  Board  again  by  reason  of  fatigue  or  other 
disability  comparisons  could  be  made  and  much  useful  knowledge  and  experi- 
ence gained. 

It  might  be  asked,  Is  all  this  trouble  worth  while?  The  medical  view 
is  that  greater  efficiency  would  be  secured  if  some  such  scheme  could  be  made 
practicable,  and  that  in  making  these  suggestions  one  is  considering  the  future 
and  the  inevitable  expansion  of  the  flying  services. 

It  Is  true  that  the  research  branch  of  the  Medical  Service  to  the  Royal 
Flying  Corps  is  still  in  its  infancy  and  that  we  have  a  great  deal  to  learn, 
but  that  is  only  an  argument  for  its  expansion  and  greater  appreciation. 

At  present  one  occasionally  finds  pilots  posted  at  a  squadron  who  from  some 
physical  defects  are  quite  unfitted  for  the  Royal  Flying  Corps  under  active 
service  conditions,  others  who  feel  sick  and  dizzy  when  banking,  and  others 
who  are  persistently  sick  after  an  hour  or  so  in  the  air. 

Their  tuition  and  training  does  not  disclose  these  failings  beforehand.  Again, 
a  pilot  is  sent  to  a  Scout  Squadron  who  fly  regularly  at  12,000  feet  to  15,000 
feet  or  more,  and  it  is  found  that  he  faints  at  15,000  feet.  On  inquiring  into 
his  history  one  discovers  that  he  has  never  previously  been  above  7,000  feet 
when  training  at  home.  His  life  and  the  value  of  the  machine  have  beeen 
risked  unnecessarily.  It  should  be  possible  on  medical  grounds  alone  to 
eliminate  or  so  distribute  sucb  cases  that  services  are  utilized  to  the  bes* 
advantage.  The  sickness  and  dizziness  could  perhaps  only  be  discovered  dur- 
ing the  training  period,  but  tests  for  determining  the  candidate's  capacity  to 
endure  high  altitudes  should  be  carried  out  during  the  preliminary  medical 
examination. 

FLYING  FATIGUE. 

Fatigue  as  ordinarily  understood  is  the  result  of  continued  hard  work  with- 
out adequate  rest.  Considered  from  this  point  of  view  alone  it  might  well  be 
understood  that  active  service  flying  would  eventually  lead  to  some  fatigue. 
The  strain  of  flying  during  the  summer  months  when  operations  are  in  progress 
is  intense,  although  the  total  number  of  hours  worked  may  not  be  great,  yet 
there  Is  the  strain  and  the  excitement  of  fighting,  the  tension  of  standing  by, 
and  the  short  and  irregular  hours  of  sleep.  There  are  no  fixed  days  or  periods 
of  rest,  no  days  when  a  fellow  can  say  to  himself  "  to-day  I  am  free,"  no  matter 
what  the  weather  is.  Nevertheless,  these  circumstances  alone  are  not  suf- 
ficient to  account  for  the  symptoms  found  when  a  pilot  gets  tired  after  three 
or  four  months'  service.  In  respect  to  hard  work,  discomfort,  and  lack  of  rest, 
the  infantryman  is  more  highly  tried  than  the  airman,  who  has  a  comfortable 
camp  and  mess  to  return  to  when  the  day's  work  is  done.  The  explanation  of 
flying  fatigue  must  be  sought  in  the  fact  that  flying  takes  a  man  into  an 
element  for  which  he  was  not  specially  designed  by  nature.  His  sense  of 
equilibration  and  the  mechanism  by  which  he  appreciates  his  position  in  space 


116  AIE  SEEVICE  MEDICAL. 

are  severely  tried,  with  the  result  that  those  who  are  less  adaptable  to  their 
environment  than  others  suffer  from  giddiness  and  sickness.  He  is  rapidly 
subjected  to  varying  changes  of  atmospheric  pressure  and  temperature. 
Further,  he  spends  a  certain  number  of  hours  each  day  in  breathing  air  de- 
prived of  its  proper  proportion  of  oxygen.  It  will  be  shown  later  that  this  fact 
is  probably  one  of  the  most  important  causes  of  flying  fatigue. 

FATIGtJE  AND  NERVES. 

A  tired  pilot  is  commonly  supposed  to  have  "  nerves."  As  a  general  state- 
ment of  fact  this  is  quite  erroneous,  and  it  is  consequently  extremely  unfortu- 
nate that  the  word  "  nerves  "  should  ever  have  crept  into  popular  talk  in  con- 
nection with  flying.  It  is  frequently,  but  by  no  means  always  true,  that  he 
is  nervous  in  the  sense  of  being  afraid  of  things  which  previously  did  not  affect 
him  in  the  least.  Still  his  nervousness  is  only  a  symptom  of  fatigue,  he  is 
suffering  no  more  from  "  nerves  "  than  a  patient  with  pneumonia  is  suffering 
from  cough.  This  use  of  the  word  "  nerves "  leads  to  a  confusion  between 
nervousness  due  to  fatigue  and  that  due  to  temperament,  a  state  of  alfairs 
that  is  most  undesirable.  Also  there  should  be  a  distinction  between  both  these 
forms  of  nervousness  and  that  which  may  follow  a  crash  where  the  pilot  or 
observer  has  been  badly  shaken  or  slightly  concussed.  In  short,  a  man  may 
suffer  from  fatigue  with  no  symptoms  of  nervousness,  or  he  may  suffer  from 
nervousness  without  being  fatigued.  It  is  true  that  in  all  cases  where  nervous- 
ness is  a  symptom  the  result  is  the  same,  namely,  the  exhaustion  of  whatever 
store  of  nervous  energy  was  originally  possessed  by  the  individual ;  still  it  is 
desirable  that. there  should  be  no  confusion  as  to  the  cause  of  the  nervousness 
in  any  given  instance. 

We  are  dealing  here  with  nervousness  only  as  it  is  a  symptom  of  fatigue, 
and  as  one  symptom  out  of  many.  Still,  before  w^e  leave  the  subject,  it  is 
desirable  to  emphasize  the  importance  of  the  effect  of  slight  concussion  upon 
the  production  of  the  train  of  symptoms  known  popularly  as  "  nerves."  A 
man  may  have  had  a  bad  crash  and  be  much  shaken,  yet  he  will  be  fit  to  fly  in  a 
day  or  two  provided  there  have  been  no  symptoms  of  concussion.  If,  as  the 
result  of  the  crash,  he  has  lost  consciousness  even  for  a  few  seconds,  if  his 
memory  is  subsequently  a  blank  as  to  events  just  before  or  after  the  crash,  if 
his  manner  has  been  strange  directly  afterwards,  then  it  may  safely  be  said 
that  he  has  had  concussion.  If,  in  addition  to  any  or  all  of  these  symptoms, 
there  is  evidence  of  a  blow  on  the  head,  the  diagnosis  is  complete. 

Unless  he  gets  adequate  rest  at  once,  he  will  lose  all  confidence  in  flying 
and  become  nervous,  shaky,  and  apprehensive. 

A  man  who  has  once  suffered  from  concussion  and  temporarily  rendered  fit 
by  a  short  period  of  rest,  will  be  liable  at  any  time  during  his  flying  career  to 
a  nervous  breakdown.  Flying  fatigue  has  no  connection  with  this  form  of 
nervousness  except  so  far  as  the  strain  of  flying  immasks  an  already  existing 
instability  or  sensitiveness  of  the  nervous  system,  due  to  previous  concussion. 

SIGNS   OF   FLYING   FATIGUE. 

(1)  Subjective.— A  man  first  notices  that  he  is  beginning  to  feel  generally 
tired,  and  that  he  has  lost  some  of  his  original  keenness.  His  sleep  does  not 
refresh  him.  He  gets  occasional  headaches.  Later  he  does  not  get  off  to 
sleep  quite  so  well  as  he  did,  or  he  may  get  off  fairly  soon,  and  yet  wake  up 
early  in  the  morning.  He  may  lose  his  appetite.  His  digestion  may  trouble 
him,  and  constipation  is  common  in  such  cases.  His  sleep  may  be  troubled 
with  dreams  of  flying  and  fighting,  and  nightmares  of  all  kinds.     He  may  notice 


AXR  SERVICE  MEDICAL.  117 

that  he  is  getting  irritable  and  that  he  can  not  stand  the  society  of  his  friends 
"en  masse,"  but  prefers  to  go  off  by  himself  and  read.  He  probably  feels  quite 
fit  and  keen  when  in  the  air,  but  has  to  force  liimself  to  go  up.  After  landing 
he  may  be  shaky  and  feel  utterly  exhausted.  He  may  be  conscious  of  his 
heart  beating,  may  awake  at  night  with  palpitation,  and  if  he  does  he  will 
find  that  he  gets  very  short  of  breath  on  exertion.  He  may  get  sick  in  the  air 
for  the  first  time  in  his  life. 

Although  he  feels  tired,  yet  fits  of  restlessness  overcome  him ;  he  can  not 
sit  down  quietly  to  read  and  write,  but  must  veed  to  be  pottering  about  the 
aerodrome.  He  may  reach  that  stage  where  he  can  not  bear  to  see  a  machine 
or  listen  to  ordinary  flying  talk. 

Sooner  or  later  he  must  give  in.  The  more  stout-hearted  he  is  the  longer  he 
disregards  nature's  danger  signals.  He  is  not  inclined  to  talk  about  his  sensa- 
tions. Any  such  thing  is  suggestive  of  "  wind  up,"  a  state  which  he  quite  abhors. 
To  keep  himself  going  he  may  rely  on  alcohol,  although  this  tendency  is  rare, 
but  he  nearly  always  smokes  too  much  for  which  no  one  can  blame  him.  He 
may  cease  to  take  trouble  about  his  flying  and  fighting  tactics.  Tired  pilots 
have  confessed  to  me  that  they  have  got  into  a  frame  of  mind  when,  if  they 
meet  any  enemy  machine,  they  feel  that  they  must  either,  turn  tail  or  go  for 
it  recklessly ;  they  can  not  trouble  to  think  about  maneuvering. 

I  am  not  sure  that  many  good  pilots  have  not  met  their  end  from  sheer 
carelessness.  They  become  too  tired  to  think.  All  these  symptoms  may  come 
on  gradually,  or  the  complete  state  of  fatigue  may  be  precipitated  by  a  bad 
crash. 

(2)  Objective  signs. — What  then  is  found  on  examination  in  such  cases? 
To  the  experienced  medical  officer  the  signs  are  unmistakable,  but  they  are 
varied,  depending  on  which  main  system  of  the  body  has  suffered  most  under 
the  strain.  One  group  may  predominate  or  all  may  be  present  in  a  varying 
degree. 

(a)  In  almost  every  case  of  fatigue  there  is  an  accentuation  of  the  normal 
heart  beat.  In  a  really  healthy  person  at  rest  this  should  be  70  to  80  beats  a 
minute,  and  there  should  be  little  difference  between  the  rate  when  he  is  sitting 
down  and  that  when  he  is  standing  up.  On  the  other  hand,  with  the  tired 
pilot,  the  pulse  rate  at  rest  is  frequently  100  a  minute,  which  rises  to  120  a 
minute  when  he  stands  up.  In  severe  cases  the  ratio  may  be  110  to  130  or 
more.  The  exercise  of  touching  the  toes  six  times  produces  an  even  greater 
rise  of  rate  in  all  such  cases. 

As  to  the  cause  and  meaning  of  this  condition  we  are  at  present  uncertain. 
It  is  similar  to  that  which  is  found  among  the  infantry  and  is  described  as 
"  soldier's  heart,"  which  is  one  of  the  symptoms  of  prolonged  strain,  but  we 
do  not  know  at  present  whether  it  is  due  to  the  same  cause.  At  any  rate,  it  is 
fairly  certain  that  the  heart  itself  is  not  diseased  in  any  way,  and  that  no 
permanent  damage  will  ensue. 

It  must,  however,  be  obvious  to  anyone,  that  if  the  slight  exercise  of  stand- 
ing up  from  a  sitting  position  produces  a  marked  rise  in  pulse  rate,  the  strain 
and  excitement  of  active  service  flying  must,  when  the  pilot  is  in  the  air,  pro- 
duce a  similar  if  not  greater  rise  of  rate,  leading  to  faintness  and  giddiness. 

A  pilot  in  this  state  not  only  can  not  possibly  be  as  alert  and  efficient  as  one 
who  is  fresh,  but  also,  there  is  the  danger  of  his  killing  himself  or  his  ob- 
server by  bad  landings. 

This  abnormal  and  sensitive  pulse  rate  is,  in  my  experience,  the  most  common 
sign  of  fatigue.  There  are,  however,  others  which  frequently  accompany  it,  but 
it  may  exist  alone. 


118  AIE  SEBVIOE  MEDICAL. 

(b)  Sometimes  the  digestive  system  suffers,  and  one  finds  a  dirty  furred 
tongue,  which  does  not  clean  with  ordinary  remedies,  and  the  patient  complains 
of  indigestion  and  abdominal  pain. 

(c)  Occasionally  the  eyesight  fails,  the  vision  becomes  hazy,  and  the  pilot 
complains  that  he  can  not  see  the  ground  clearly  to  land,  and  has  difficulty  in 
picking  out  enemy  machines.  There  may  be  no  direct  defect  of  vision  at  all,  but 
more  frequently  there  is  some  slight  error  which  he  was  previously  able  to 
correct  by  the  unconscious  muscular  power  of  the  eye.  The  muscle  gets  tired 
with  the  strain,  and  the  defect  shows  itself.  A  few  days'  rest  has  been  suffi- 
cient, in  the  few  cases  I  have  seen,  to  i-estore  normal  vision  once  more. 

(d)  Finally,  what  evidence  does  the  medical  officer  find  of  "nerves?"  The 
subjective  sensations,  the  nervousness,  the  iritability,  and  so  forth,  have 
already  been  described.  Some  patients  talk  freely  on  the  subject,  while  from 
others  the  information  can  be  obtained  by  judicious  questioning.  The  objective 
signs  are  simple,  a  tremor  of  the  hands  and  of  the  tongue  when  protruded,  and 
what  is  known  in  medical  language  as  "  an  exaggeration  of  the  deep  reflexes." 
Normally,  when  the  tendon  of  a  muscle  is  smartly  tapped,  the  muscle  will  re- 
spond by  contracting.  If  there  is  any  interference  with  the  nerve  supply  to  the 
muscle,  it  will  not  contract  at  all,  while,  if  the  nervous  system  generally  is  in 
an  irritable  state,  the  contraction  will  be  much  quicker  and  fuller  than  normal. 

One  does  not,  by  any  means,  always  find  these  signs  in  pilots  who  are  suffer- 
ing only  from  fatigue.  If  they  have  had  some  severe  nervous  shock,  such  as  a 
bad  crash,  or  have  been  shot  about,  then  all  or  any  of  them  may  be  expected. 
If  there  has  been  no  severe  nervous  shock,  nervousness  is  one  of  the  late  symp- 
toms of  fatigue,  and  it  should  be  our  object  to  see  that  the  tired  pilot  never 
reaches  the  stage  of  "  nerves "  because  he  will  probably  take  the  longer  to 
recover. 

OXYGEN    STAEVATION. 

What  evidence  have  we  at  present  that  "  oxygen  starvation  "  plays  any  part 
in  fatigue?  Two  facts  can  be  brieiiy  mentioned  here.  It  is  now  well  recog- 
nized that  pilots  and  observers  of  long  distance  high-flying  machines,  such  as 
the  D.  H.  4,  feel  extremely  tired  and  exhausted,  not  only  after  landing,  but  also 
during  the  following  day  in  some  cases,  unless  they  have  been  provided  with 
oxygen. 

Secondly,  experiments  have  been  carried  out  to  test  the  effect  of  altitude  on 
mental  concentration.  An  individual  used  to  the  air  is  tested  on  the  ground 
with  an  apparatus  for  measuring  his  reaction  time,  a  kind  of  scientific  game 
of  "  snap."  He  is  then  taken  up  to  5,000  feet  only  and  brought  down  again. 
On  landing,  he  is  again  tested,  and  it  is  found  that  his  reaction  time  is  dis- 
tinctly slowed  down,  and  his  mind  is  not  so  alert  as  it  was  before. 

Those  who  have  ascended  to  great  heights  in  balloons  have  recorded  how 
their  senses  have  become  almost  paral.yzed,  and  they  have  had  to  make  the 
most  intense  effort  to  take  the  necessary  steps  to  come  down. 

It  is  probable  then  that  further  research  will  definitely  prove  oxygen  starva- 
tion plays  a  considerable  part  in  the  causation  of  flying  fatigue. 

Those  who  live  permanently  at  high  altitudes  gi'adually  get  used  to  the  rarl- 
fied  air,  their  blood  undergoing  certain  compensatory  changes.  It  has  been 
proved  that  no  such  change  takes  place  in  the  blood  of  a  high-flying  pilot. 

It  is  worth  noting,  however,  that  there  are  some  people  who  are  very  little  af- 
fected by  heights  which  will  render  the  average  person  quite  uncomfortable. 
They  can  go  to  15,000  or  even  to  18,000  feet  and  do  not  experience  any  of  the 
usual  sensations,  nor  do  they  feel  anything  like  so  tired  afterwards. 

The  reason  for  this  is  still  obscure,  but  it  has  something  to  do  with  the  efficiency 
of  the  lungs.    There  is  a  simple  means  of  testing  this  efficiency,  namely,  to 


AIB  SEE7I0E  MEDIOAL.  119 

see  how  one  can  hold  one's  breath.  Two  or  three  deep  breaths  are  taken  In 
and  out;  the  lungs  are  then  filled  to  their  utmost  capacity  and  the  breath  is 
held  for  as  long  as  possible.  Forty-five  seconds  is  a  minimum  time ;  anything 
less  than  this  means  that  the  individual  will  not  be  able  to  stand  hard  work 
in  the  air,  even  at  moderate  altitudes;  the  longer  he  can  hold  his  breath  the 
better  will  he  be  able  to  stand  high  altitudes  without  fatigue  and  distress. 

There  are  more  accurate  motliods  than  this  rough  test,  but  it  is  nevertheless 
a  reliable  guide. 

FATIGUE   AND   EFFICIENtfr. 

Before  putting  forward  suggestions  as  to  the  remedy  for  these  troubles,  a 
brief  allusion  to  the  relations  between  work,  fatigue,  and  efiiciency  may  be 
made.  Reasons  will  be  given  as  to  why  it  would  be  true  economy  to  take  all 
possible  steps  to  prevent  fatigue,  and  why  this  would  result  in  greater  efiiciency. 

It  has  been  proved  over  and  over  again  in  industrial  life  that  continuous  hard 
work  without  adequate  rest  tends  in  the  long  run  to  lower  the  quality  of  the 
work  turned  out.  This  was  seen  in  the  earlier  days  of  the  war  when  the 
munition  factories  worked  overtime  and  on  Sundays.  In  a  fuse  factory,  for 
instance,  the  gross  output  was  increased  with  overtime  and  Sunday  work, 
but  so  much  had  to  be  scrapped  owing  to  bad  workmanship  that  the  net  out- 
put of  perfect  fuses  diminished  after  a  week  or  two  but  rose  again  as  soon  as 
Sunday  work  was  abolished. 

It  must  be  remembered  that  the  general  level  of  efficiency  of  any  group  of 
workers  depends  not  on  a  few  brilliant  and  tireless  performers,  but  upon  the 
average  individuals  of  the  group.  So  also  must  be  the  case  in  a  Flying  Corps 
Squadron.  The  puce  must  be  set  by  the  capacities  of  the  average  member. 
This  will  not  prevent  extra  work  being  put  in  by  those  of  stouter  metal,  but 
on  medical  grounds  the  average  and  inferior  members  should  not  be  screwed 
up  to  the  level  of  those  who  are  specially  gifted  to  stand  strain  and  fatigue. 
If  this  is  done  it  means  that  there  is  a  constant  wastage  from  fatigue,  thereby 
preventing  in  many  cases  the  average  man  from  reaching  that  stage  of  ex- 
perience attained  by  the  tougher  members  of  the  squadron. 

An  illustration  of  the  value  of  experience  is  provided  by  the  monthly  casualty 
lists  of  the  Brigade.  In  the  first  six  months  of  this  year,  the  battle  casualties 
among  pilots  and  observers  during  the  first  two  months  of  service  were  53 
per  cent,  the  lowest  ratio  being  43  per  cent  and  the  highest  81  per  cent. 

It  should,  therefore,  be  the  object  of  those  concerned  with  personnel  that  the 
experienced  individual  is  not  wasted  by  the  premature  onset  of  fatigue,  pre- 
mature in  the  sense  of  its  being  preventable.  The  conditions  at  present  tend 
to  cause  overwork  among  the  more  experienced  members  of  the  squadron. 
First  because  there  is  insuflicient  care  in  the  medical  selection  of  new  pilots. 
A  new  pilot  is  posted  who  is  really  unfit  for  the  work,  several  days  may  elapse 
before  the  fact  is  obvious,  and  several  more  are  wasted  before  he  is  replaced 
owing  to  the  necessary  inquiries  and  formalities.  Again,  a  similar  result  is 
effected  by  the  falling  out  from  fatigue  of  those  who  can  not  keep  up  with  the 
pace  set.    Finally,  in  his  turn,  the  tough  and  experienced  man  gives  in. 

It  is  not  denied  that  whatever  is  done,  something  of  the  kind  is  bound  to 
happen  eventually,  but  it  is  suggested  that  the  onset  of  fatigue  could  be  post- 
poned by  appropriate  measures  and  that  a  squadron  would  thereby  gain  a 
greater  accumulation  of  experience,  and  a  greater  output  of  good  work  would 
result. 

THE  EEMEDY. 

In  order  to  delay  the  onset  of  fatigue,  there  should  be .  either  more  rest  or  less 
work,  and  oxygen  should  be  in  general  use  for  all. 


120  AIR  SERVICE  MEDICAL. 

I 

My  own  opinion  is  that  there  would  be  no  necessity  to  cut  down  the  work 
if  everyone  could  be  certain  of  a  complete  day  of  rest  at  stated  intervals,  no 
matter  what  the  weather  was.  Then,  particularly  if  any  such  scheme  is 
impracticable,  there  should  be  a  Flying  Corps  rest  station  similar  to  the  existing 
corps  rest  stations.  It  should  be  situated  well  back  some  10  miles  or  so  from 
the  aerodromes  in  some  quiet  and  pleasant  spot.  Here  could  be  sent  those 
who  could  reasonably  be  expected  to  return  to  duty  within  10  days,  no  matter 
from  what  they  were  suffering.  It  would  receive  those  who  are  suffering  from 
a  slight  shock  as  the  result  of  a  crash,  those  vrith  some  minor  ailment,  as  well 
as  those  who  are  beginning  to  feel  the  effects  of  fatigue  early  in  their  period 
of  service,  owing  to  some  particularly  strenuous  time  of  overwork. 

The  recuperative  powers  of  the  young  are  remarkable,  so  long  as  the  period 
of  strain  and  exhaustion  has  not  been  too  long.  A  child  will  recover  from  a 
short  acute  illness  far  better  than  from  a  long  period  of  ill  health ;  so  also 
a  young  pilot  subjected  to  a  short  period  of  severe  strain  may  be  apparently 
exhausted,  but  will  rapidly  recover  with  a  few  days'  rest  on  the  ground. 

Whatever  he  is  suffering  from,  it  is  better  for  him  to  be  sent  right  away  from 
the  life  and  noise  of  the  aerodrome ;  he  will  return  the  fresher  and  the  more  fit 
for  work.  It  is  true  that  in  slack  time  he  can  go  to  a  clearing  station  and 
rest,  but  in  busy  times  he  can  not  be  kept  there  and  must  be  evacuated  to 
make  room  for  others. 

SUMMARY    AND    CONCLUSIONS. 

Flying  fatigue  is  a  special  form  of  fatigue  which  is  due  to  the  strain  of 
service  upon  an  individual  whose  powers  of  endurance  are  weakened  by  his 
having  to  spend  so  many  hours  each  day  in  an  atmosphere  lacking  in  oxygen 
and  by  the  severe  strain  of  fighting  or  observing.  This  means  that  at  the 
time  when  his  nervous  system  and  his  muscles  are  required  to  work  most 
efficiently  they  are  in  reality  working  at  a  disadvantage  because  the  blood 
which  nourished  them  is  deficient  in  oxygen.  The  result  is  fatigue  which 
eventually  shows  itself  by  the  various  signs  which  have  been  described. 

A  crash,  a  severe  shock,  or  slight  concussion,  may  unmask  existing  fatigue 
and  cause  the  nervous  symptoms  and  signs  to  predominate.  Otherwise  it  is 
not  usual  for  the  tired  pilot  to  show  any  objective  signs  of  "  nerves  "  until  he 
becomes  tired  indeed. 

It  is  desirable  that  he  should  be  given  a  rest  before  he  reaches  this  stage, 
and  it  is  suggested  that  in  the  early  stage  of  fatigue  a  few  days'  complete  rest 
away  from  the  squadron  might  save  an  early  breakdown. 

The  remedies  for  fatigue  are  more  opportunities  for  rest  and  the  more  gen- 
eral use  of  oxygen. 

It  is  proposed  that  the  medical  examination  of  candidates  should  be  more 
strict,  that  no  pilot  should  be  posted  to  work  for  which  he  is  unfitted  by  some 
physical  defect  or  individual  peculiarity,  it  being  possible  to  tell  whether 
anyone  can  stand  high  altitudes  without  ill  effect.  In  this  way  greater 
economy  and  efficiency  of  personnel  could  be  effected. 

It  is  expected  that  the  more  general  use  of  oxygen  will  do  away  with  a  great 
deal  of  the  trouble  experienced  from  early  fatigue,  and  enable  many  to  become 
efficient  pilots  and  observers  who  would  otherwise  be  unable  to  stand  the  strain. 

Research  and  the  opportunities  for  research,  are  both  urgently  needed  for  the 

investigation  of  this,  and  many  other  medical  questions  connected  with  flying. 

Dudley  Cobbett, 

Lieut.  R.  A.  M.  C,  Medical  Officer  i/c  5th  Brigade, 

Royal  Flying  Corps. 
August  3,  1917. 


AIR  SERVICE  MEDICAL.  121 

A  good  deal  of  this  is  now  quite  crude;  it  is  written  only  in  the  light  of  rough 

elinicnl  observation,  for  the  information  of  the  lay  and  military  mind. 

Dudley  Cobbett, 

Capt.,  R.  A.  M.  C, 

24th  General  Hospital. 
December  12,  1917. 

The  following  letter  was  written  by  Maj.  Birley  on  January  14, 
1918: 

We  are  trying  to  improve  the  Flack  experiment.  At  present  it  is  chiefly 
useful  for  discovering  those  very  rare  cases  of  men  with  apparently  healthy 
hearts  and  lungs,  who  are  nevertheless  so  sensitive  to  reduced  oxygen  pressure 
that  they  can  not  fly  above  7,000  to  8,000  feet.  It  is  quite  clear  that  a  study 
of  the  pulse  during  the  experiment  is  going  to  give  results  of  more  importance 
than  can  be  obtained  be  merely  determining  the  percentage  of  oxygen  at 
which  a  man  begins  to  lose  consciousness.  In  other  words,  we  are  trying  to 
find  out  how  a  man  reacts  to  diminished  percentages  of  oxygen.  The  short 
period  covered  by  the  test  in  its  present  form,  together  with  the  fact  that  the 
amount  of  oxygen  available  is  not  under  control,  has  led  us  to  attempt  some- 
thing better.  Dreyer  is  getting  on  to  it,  but  the  rough  idea  is  to  have  an 
air  space  into  which  the  subject  breathes  which  can  be  filled  with  varying 
proportions  of  nitrogen  or  oxygen  at  the  will  of  the  experimenter.  In  this  way 
we  can  prolong  the  experiment  to  any  extent,  vary  the  composition  of  the 
air,  and  in  fact,  have  all  the  advantages  of  the  exhaustation  chamber  miniis  the 
expense  and  unpleasantness  of  exposing  one's  self  to  low  pressures.  I  am  ex- 
pecting Sydney  Scott  at  the  end  of  the  month.  Can  you  lend,  give,  or  sell  us 
one  of  your  turning-chairs?  " 
Yours,  sincerely, 

James  L.  Beblet, 
Major,  R.  A.  M.  C. 

The  following  report  is  from  one  of  our  officers : 

I  visited  dilTerent  squadron  groups  at  the  British  Front  and  had  the  oppor- 
tunity to  talk  intimately  with  many  pilots  and  observers.  The  following  inci- 
dents serve  as  an  illustration  of  the  life  and  activities  of  these  young  aviators : 

I  was  sitting  at  mess  with  Major  D.  when  a  pilot  entered  and  reported 
that  he  had  just  dropped  bombs  on  the  German  trenches  from  the  height  of  500 
feet.  He  had  maneuvered  the  machine  in  such  a  way  that  there  had  occurred 
only  a  few  shots  through  the  aeroplane,  and  some  queer  missile  had 
ripped  through  the  back  of  the  overcoat  and  coat  of  the  observer,  but  had 
merely  taken  the  skin  off  of  the  back  of  his  neck.  A  few  minutes  later  this 
observer  appeared  with  a  bandage  about  his  neck.  Both  the  pilot  and  ob- 
server then  sat  down  for  their  lunch,  and  the  incident  was  apparently  for- 
gotten as  being  merely  a  part  of  the  day's  work.  It  would  be  highly  profitable 
to  other  officers  of  the  Air  Service  as  well  as  medical  officers  to  become  familiar 
with  the  actual  life  of  the  fliers  at  the  front. 

One  can  learn  most  in  sitting  round  the  fire  at  night  in  intimate  conversa- 
tion with  these  young  men.  Their  extreme  youth  is  striking ;  one  observer,  age 
about  18,  had  the  face  of  a  baby,  and  yet  was  known  to  be  a  courageous  and 
efficient  man,  especially  clever  in  manipulating  a  machine  gun.  These  men 
were  interested  to  hear  about  the  ear  as  the  oi'gan  of  balance,  and  also  enthusi- 
astically approved  the  idea  of  our  plan  for  the  CARE  OF  THE  FLIERS.  They 
feel  it  would  be  a  "  wonderful  thing  "  to  have  a  high-grade,  specially  trained 


122  Am  SERVICE  MEDICAL. 

physician  living  among  them,  to  whom  they  could  go  with  the  same  freedom  in 
which  they  were  accustomed  to  go  to  their  family  physician  at  home.  They  volun- 
teered the  thought  that  many  times  when  they  were  not  feeling  well  they  would 
never  think  of  going  to  the  commanding  oflBcer  with  their  troubles  for  fear  that 
he  would  think  they  were  "  swinging  the  load  "  (British  slang  for  "  malinger- 
ing"). On  the  other  hand,  if  they  were  with  a  medical  officer  whom  they 
trusted  and  looked  to  for  advice,  they  would  not  hesitate  to  tell  their  woes  to 
him  freely.  These  shrewd  youngsters  were  able  even  among  themselves  to 
detect  the  beginning  of  a  nervous  breakdown  iB  one  of  their  fellow  pilots.  One 
aviator  said  "  Do  you  see  that  chap  over  there ;  he  is  laboring  under  his  present 
work;  he  has  no  idea  himself  that  there  is  anything  the  matter  with  him  or 
that  he  is  working  under  special  strain.  He  has  been  at  it  for  three  months, 
but  I  can  tell  that  what  used  to  be  a  spontaneous  and  enthusiastic  work  on  his 
part  has  now  become  a  downright  labor  which  he  has  to  force  himself  to 
carry  out."  It  impressed  me  that  if  these  medically  untrained  boys  could 
analyze  the  physical  state  of  their  comrades  how  much  better  could  this  be 
done  by  an  older  "  comrade."  a  medical  adviser  who  was  not  only  specially 
trained  in  the  care  of  the  flier,  but,  and  very  important,  one  who  was  selected 
for  his  personalitjf  and  ability  to  "  get  under  the  skin  "  of  these  pilots  and 
observers.  Such  a  medical  officer  attached  to  squadron  groups  should  fulfill 
the  function  of  a  friend  to  the  flier  as  well  as  giving  him  scientific  observation 
and  care.  It  can  be  stated  without  reservation  that  such  a  person  would  be- 
come a  powerful  factor  in  lifting  and  maintaining  the  morale  of  these  flying 
officers.  This  was  heartily  approved  by  them,  and  they  said  they  were  sorry 
that  such  a  plan  could  not  be  carried  out  for  them.  It  is  probable 
that  a  sufficient  number  of  British  Medical  Officers  can  not  be  spared  for  such 
a  service,  and  it  seems  to  me  that  it  is  perfectly  possible  and  highly  desirable 
that  we  should  offer  a  dozen  or  more  of  our  trained  specialists  to  be  attached 
in  this  capacity  as  Medical  Advisers  to  the  commanding  officers  of  the  British 
.squadron  groups.  Director  Gen.  T.  H.  Goodwin,  of  the  Royal  Army 
Medical  Corps,  would  appreciate  such  help  from  us,  and  on  our  part  such  a  con- 
tribution could  be  very  easily  arranged,  as  we  have  not  only  such  a  large  num- 
ber of  physicians  in  our  service,  but  such  a  large  number  of  those  specially 
trained  in  the  States  for  the  care  of  the  flier.  These  American  officers  could 
work  under  the  direction  of  Maj.  James  L.  Birley. 

The  trip  back  from  the  British  front  was  made  by  auto  with  Capt. 

T ,  who  is  in  charge  of  British  squadrons  devoted  exclusively 

to  night  flying.  (Capt.  T has  had  600  hours  in  the  air  day  fly- 
ing and  200  hours  of  night  flying. )  He  asked  me  if  there  was  any  medi- 
cal explanation  for  the  following:  Many  experienced  aviators  have 
been  sent  to  him  who  had  no  difficulty  whatever  in  flying  in  the  day- 
time, and  yet  he  found  them  to  be  unfit  for  night  flying.  I  sug- 
gested that  an  examination  of  their  ear  mechanism,  either  by  the 
turning-chair  or  the  caloric  test,  would  be  highly  desirable,  and  that 
very  possibly  the  uncertainty  of  these  individuals  flying  at  night 
might  be  attributed  to  a  poor  sense  of  balance  which  had  not  been  in 
evidence  in  their  day  flying,  because  they  had  been  able  to  maintain 

their  balance  by  the  sense  of  sight.     Capt.  T then  said  that  he 

wished  all  such  men  could  have  such  an  ear  examination  before  they 
were  sent  to  him  for  night  flying  work. 


AIB  SEEVIOE  MEDICAL.  123 

A  visit  to  England,  including  London  and  flying  camps  in  Eng- 
land, enables  us  to  become  familiar  with  the  British  technique  of 
examination  of  the  applicants  for  the  flying  corps,  and  also  to  study 
their  methods  for  the  medical  care  of  the  aviator  in  the  flying 
schools.  The  experts  of  the  British  forces,  both  at  the  front  and  also 
in  England,  emphasized  their  approval  of  our  plans  for  the  physical 
care  of  the  flier. 

FRENCH. 

The  French  have  placed  the  examination  of  candidates  for  the 
Aviation  Service  in  the  hands  of  specialists  who  have  carried  out  much 
experimental  work  of  value  in  this  study,  especially  in  the  problem 
of  OXYGEN  INSUFFICIENCY.  Prof.  Josue  has  been  in  charge 
of  the  cardio-vascular  work,  and  Prof.  Lombard  in  charge  of  the  ex- 
aminations of  the  internal  ears  and  the  balance  mechanism.  Dr.  Gar- 
saux  has  conducted  the  experimental  work  in  regard  to  the  oxygen 
problem  at  the  Aero-Technique  Institute.  The  institute  contains  an 
excellent  vacuum  chamber  in  which  experimental  work  has  been  car- 
ried out  for  many  months.  As  one  result  of  this  work  there  has  been 
produced  the  Garsaux  oxygen  apparatus,  so  constructed  as  to  give, 
automatically,  an  increasing  amount  of  oxygen  with  each  increase  in 
altitude.  A  complete  description  of  the  Garsaux  oxygen  apparatus 
and  a  description  of  the  vacuum  chamber  are  in  our  possession,  also 
an  article  written  by  Dr.  Garsaux,  "  Sur  le  Mai  des  Aviateurs  et  les 
Moyens  a  employer  pour  I'Eviter." 

At  this  writing,  toward  the  end  of  January,  1918,  there  is  planned 
a  complete  reorganization  of  the  French  Medical  Aviation  Service, 
and  it  is  contemplated  that  Prof.  Nepper  will  be  put  in  charge  of 
this  work.  We  have  in  our  possession  the  standards  and  requirements 
of  the  French  Aviation  Service,  both  of  the  Army  and  of  the  Navy. 
It  is  striking  to  note  that  the  French,  like  their  allies,  were  not  able  to 
bring  about  during  the  early  part  of  the  war  a  special  study  of  the 
medical  problem  of  the  flier.  It  was  not  recognized  that  such  a  study 
was  at  all  necessary  for  the  efficiency  of  the  Air  Service.  Now,  how- 
ever, those  in  authority  have  cx)me  to  recognize  the  need  for  such 
special  medical  work. 

The  French  medical  officers  said  that  they  would  gladly  meet  with 
us  and  with  the  medical  officers  who  were  working  along  similar 
lines  in  the  British  and  Italian  service  in  order  that  through  an  in- 
formal exchange  of  ideas  we  might  all  obtain  the  benefit  of  each 
others'  experiences  in  this  study.  Such  an  informal  meeting  would  be 
highly  desirable  and  should  perhaps  most  suitably  be  arranged  to 
take  place  in  Paris. 

The  following  article  by  Dr.  Guilbert,  attached  to  the  French 
Aviation  Service,  is  included,  particularly  as  it  is  written  for  the  in- 


124  AIB  SERVICE  MEDICAL. 

struction  of  the  aviator  himself  and  shows  that  the  French  have  a 
similar  viewpoint  to  ours  in  regard,  not  only  to  the  examination,  but 
also  to  the  CAEE  of  the  flier. 

PHYSIOLOGY,  PHYSICAL  INAPTITUDE,  AND  HYGIENE  OF  THE  AVIATOR. 

[Lecture  by  Dr.  Guilbert,  attached  to  French  Air  Service.     Translated  from  the  French 

by  Maj.  Ealph  Goldthwaite,  M.  C] 

I.   PHYSIOLOGT. 

At  a  time  when  aviators  are  multiplying  and  astonishing  us  by  their  prowess, 
it  is  useful  to  recall  some  ideas  on  physiology  which  may  interest  us,  and 
some  principles  of  hygiene  which  you  should  observe. 

The  aviator  is  often,  with  good  reason,  compared  to  the  bird.  The  bird 
does  not  fly  by  any  marvelous  or  extraordinary  process.  He  rests  on  the  air ; 
and  the  aviator  does  the  same  thing.  But  between  them  there  exists  a  marked 
difference,  in  that  the  bird,  when  he  flies,  is  in  his  own  element ;  man,  on  the 
contrary,  intended  for  life  on  the  earth,  has  need,  when  he  undertakes  this 
extraordinary  sport,  not  only  of  all  his  physical  energy,  but  in  addition  all  his 
moral  force  and  his  intelligence,  and  he  can  not  leave  anything  to  chance. 
That  is  to  say,  in  aviation,  physiology  plays  a  large  part. 

The  aviator  first  of  all  should  keep  a  calm  and  cool  attitude  of  mind,  and  not 
exaggerate  his  reflexes,  but  should  know  how  to  utilize  them  rapidly.  He 
must  be  the  master  of  his  impressions  and  be  ready  to  make  a  prompt  decision 
and  have  knowledge  of  the  smallest  of  his  movements. 

On  the  subject  of  proper  equilibrium,  it  is  especially  custom  which  will  give 
these  qualities.  Violent  reactions  and  poor  equilibration  at  the  start  will  often 
disappear  with  training,  for  one  becomes  accustomed  to  sensations  of  being  in 
the  air,  as  to  all  others. 

These  sensations  are  quite  different  than  the  general  public  imagines.  It  is 
generally  believed  that  the  rise  and  descent  of  an  aeroplane  are  accompanied 
by  uncomfortable  feelings  similar  to  those  produced  by  riding  in  an  elevator. 
It  is  often  thought  that  the  movements  of  the  apparatus  would  give  the  pilot 
or  passenger  vertigo,  or  a  sort  of  seasickness,  and  in  fact  it  is  quite  astonish- 
ing that  this  is  not  the  case.  The  absence  of  vertigo  in  the  healthy  individual 
results  from  the  isolated  independence  of  the  apparatus.  On  the  ground,  when 
one  happens  to  be  in  a  place  which  is  high  and  dangerous,  and  where  one  sees 
the  wide  expanse  around  him,  one  has  a  feeling  of  being  insufliciently  sus- 
tained, one  fears  that  the  support  will  give  way,  hence  the  impression  of  fear 
and  vertigo. 

In  an  apparatus  in  flight  there  is  nothing  of  this  sort.  There  is  complete 
separation  from  the  earth,  which  appears  then  as  an  absolutely  strange  ele- 
ment. The  apparatus  as  a  whole,  its  area,  its  speed,  all  contribute  to  suppress 
the  causes  of  attraction,  and  especially  of  vertigo.  All  this  is  so  true,  that 
one  often  sees  individuals,  who  can  not  lean  out  of  a  window  without  feeling 
dizzy,  who  have  no  such  sensation  in  the  course  of  an  ascent  in  an  aeroplane. 
It  is  a  fact  that  there  are  few  places  where  one  can  obtain  such  an  impression 
of  calmness  and  immobility  as  in  an  aeroplane.  It  very  often  seems  as  if  one 
did  not  move,  and  it  is  only  by  observing  the  ground  that  one  becomes  certain 
of  his  progress.  In  full  flight,  a  feeling  of  security  comes  upon  you ;  one  sees 
the  objects  of  the  earth  grow  smaller  and  then  disappear.  Little  attention  is 
given  to  the  successive  crossings  of  zones  of  air  more  and  more  cold,  and  less 
and  less  dense.  One  does  not  realize  that  the  conditions  of  existence  must 
change,  and  that  the  organs  must  adjust  themselves  to  these  conditions.    Con- 


AIR  SEBVIOE  MEDICAL.  125 

sequently,  as  long  as  tliey  are  intact  and  resistant  they  should  be  capable 
of  repeating  these  efforts  indefinitely. 

In  a  general  way,  flights  are  made  at  a  great  altitude,  the  ascent  is  more 
or  less  rapid,  and  from  the  highest  point  the  aeroplane  redescends  toward 
the  ground  often  too  rapidly;  the  great  speed  of  the  ascent  and  dizzy  descent 
are  the  two  principal  factors  which  produce  aviators'  sickness  of  which  so 
much  has  been  said  the  last  few  years,  especially  at  the  Academy  of  Medicine. 

Doctors  and  professional  aviators  have  noticed  that  during  the  ascent,  respi- 
ration becomes  shorter,  the  heart  beats  faster,  up  to  a  height  of  1,500  meters. 
At  this  altitude  the  pilot  may  be  taken  with  nausea  and  a  sensation  of  dila- 
tion of  the  stomach,  vision  may  become  less  clear,  although  at  2,000  meters,  in 
general,  the  visual  acuity  increases  by  a  third  by  reason  of  the  congestion 
of  all  the  organs  of  the  head,  and  in  particular  of  the  choroid  and  of  the 
retina.  The  throat  may  give  the  impression  of  a  feeling  of  dryness,  the  ears 
may  ring  and  have  a  sensation  of  obstruction.  The  nose  is  insufficient,  and 
the  pilot  must  open  his  mouth  to  assist  him  in  breathing.  He  may  also  be 
taken  with  a  desire  to  sleep,  he  may  become  apathetic,  and  movements  become 
painful,  nervous  or  jerky,  and  of  an  unusual  amplitude. 

In  the  descent,  the  heart  beats  stronger,  but  without  acceleration ;  the  heart 
beats  increase  in  volume  and  in  proportion  to  the  rapidity  of  the  descent.  It 
is  difiicult  to  give  an  account  of  what  happens  as  regards  respiration,  by  reason 
of  the  rapidity  of  the  fall,  which  causes  a  sort  of  physical  anguish.  As  for  the 
ringing  of  the  ears,  that  tends  to  increase  toward  the  end  of  the  descent,  ac- 
companied perhaps  by  small  hemorrhages.  At  the  moment  of  reaching  the 
earth,  buzzing  of  the  ears  may  be  of  such  intensity  that  the  pilot  is  deaf  and 
can  not  even  hear  his  motor  by  osseous  transmission.  He  feels  a  sensation  of 
disagreeable  tension  in  the  ears,  due  to  the  difference  of  pressure  which  occurs 
on  the  two  sides  of  the  drum,  on  the  one  side  the  exterior  atmospheric  pres- 
sure, and  on  the  other  side  the  intratympanic  pressure,  and  perhaps  the  intra- 
vascular. 

This  sensation,  very  common  as  it  is  on  the  bimotors,  may  at  times  persist 
for  a  long  time  but  ends  usually  after  some  movements  of  swallowing,  which 
open  up  the  orifices  of  the  Eustachian  tubes. 

When  one  decides  to  come  to  earth,  by  making  a  blowing  effort  with  nose  and 
mouth  closed,  at  two  or  three  hundred  meters  from  the  ground,  one  can  inflate 
the  ears  and  thereby  avoid  the  heavy  feeling  in  the  head  and  the  painful  sensa- 
tions on  the  throat. 

But  there  is  still  another  series  of  phenomena  which  increases  clearly  in  pro- 
portion as  one  approaches  the  ground.  It  is,  first,  the  sensation  of  smarting  in 
the  face,  with  reddening  and  very  high  color.  The  eyes  sting,  and  are  injected ; 
the  nostrils  are  moist,  then  comes  headache,  or  more  exactly  a  sort  of  heavy 
feeling  in  the  head  with  a  sensation  of  obstruction,  a  swelling  up  in  the 
pharynx  at  the  level  of  the  larynx.    Finally  there  is  a  strong  tendency  to  sleep. 

To  explain  these  different  difficulties  one  may  admit  that  an  organism  which 
falls  to  the  earth  in  four  or  five  minutes,  or  less,  after  having  attained  three  or 
four  thousand  meters  of  elevation  in  twenty  minutes,  has  not  had  the  time  to 
adapt  its  circulatory  system  to  the  different  barometric  pressures,  which  are 
changing  rapidly.  For  example,  a  change  from  591  mm.  of  mercury  pressure, 
at  2,000  meters,  to  760  mm.  mercury  on  the  ground.  All  these  uncomfortable 
sensations  experienced  by  certain  aviators  in  their  ascents  and  descents,  which 
seem  to  have  been  the  cause  occasionally  of  fatal  accidents,  prove  the  necessity 
for  all  aviators  of  having  absolutely  normal  sensory  organs :  respiratory,  circu- 
latory, urinary,  and  locomotor,  as  well  as  a  perfect  play  of  the  nervous 
functions. 


126  AIR  SERVICE  MEDICAL. 

This  leads  me  to  open  up  a  new  question  which  is  important  for  you,  and 
often  delicate  to  me — I  wish  to  speak  of  the  physical  inaptitude  of  being  a 
pilot,  and  also  causes  which  may,  at  times,  modify  a  previous  aptitude.  It  gen- 
erally costs  a  good  many  candidates  to  find  out  those  who  are  inapt,  whether 
it  be  medical  examination  or  from  the  opinion  of  the  monitors.  They  should 
understand  perfectly  that  their  personal  interest  is  at  stake  as  well  as  the  in- 
terest of  the  country.  Aviation,  already  perilous  for  those  who  have  a  particular 
aptitude  for  it,  will  be  certainly  fatal  to  one  who  has  not  this  aptitude.  There 
are  abundant  examples  of  this  point.  But  certain  men  see,  in  the  fact  of  their 
inaptitude,  a  reflection  on  their  pride,  which  has,  however,  nothing  to  do  with 
the  question.  No  one  can  pretend  to  be  fit  for  everything.  How  many  among 
you  are  there  who  would  have  no  disposition,  for  example,  for  music,  painting, 
fencing,  equitation,  and  yet  you  do  not  feel  yourselves  humiliated?  There  is  no 
more  reason  to  desire  to  be  necessarily  suited  for  aviation,  which  is,  in  a  way, 
a  kind  of  art.  After  this  digression,  let  us  return  to  the  main  subject — physical 
inaptitude. 

II.   PHYSICAL    INAPTITUDE, 

As  for  that,  I'm  going  especially  to  bring  myself  down  to  observations  that  I 
have  gathered  together  concerning  scholars  who  have  not  been  able  to  succeed 
in  obtaining  their  brevet,  since  my  arrival  at  the  school.  Each  one  may  obtain 
information  which  is  useful  in  filling  certain  gaps  in  his  physical  make-up.  He 
will  also  be  able  to  modify  his  conceptions  of  the  proper  care  of  an  aeroplane, 
and  render  his  make-up  and  the  apparatus  in  accord.  I  will  tell  you  nothing  of 
the  deaths  which  come  to  my  mind,  but  I  leave  to  you  the  care  of  inquiring  for 
yourselves  as  to  witnesses  and  details  of  a  fall,  and  the  probable  causes  which 
have  led  up  to  it. 

As  far  as  one  has  been  able  to  judge,  certain  types  of  aeroplane  are  better 
suited  to  certain  individuals,  I  will  refer  only  to  those  who  have  been  dis- 
charged from  the  service  for  their  professional  or  physical  inaptitude.  Setting 
aside  the  question  of  intelligence,  the  human  machine  should  respond  to  certain 
physical  conditions.  Pilots  should  be  young  men,  capable  of  rapid  reaction, 
though  it  is  difficult  to  fix  the  limit  of  age  in  a  definite  way.  One  may  say, 
however,  that  as  time  goes  on,  before  giving  intensive  service  at  the  front,  a 
student  pilot  should  not  have  passed  30  years  of  age.  There  are,  however, 
exceptions.  Certain  subjects  have  the  faculty  of  saving  their  organs  in  their 
youthful  condition,  particularly  those  adept  in  sports;  these  make  usually  tlie 
best  aviators,  even  if  their  age  is  relatively  advanced.  Young  pilots  have  rapid 
and  exact  reactions,  and  are  less  sensitive  to  cold.  It  is  necessary  to  note 
that  in  growing  old  the  sensitiveness  to  cold  is  much  greater;  which  seems  to 
explain,  in  my  opinion,  the  fatigue  of  the  arteries  and  kidneys  in  particular.  It 
is  known  that  the  oxygen  diminishes  proportionately  as  one  goes  up  in  the  air. 
Respiratory  exchanges  become  more  diflicult,  the  blood  gets  rid  of  its  toxins 
with  greater  difficulty,  and  there  is  greater  necessity  for  elimination  by  the 
kidneys,  which  are  the  other  eliminative  organs  for  poisons.  And  in  the  same 
measure  the  skin  must  furnish  assistance,  or  otherwise  an  excess  of  toxins 
,  will  occur  in  the  blood,  causing  pains  in  the  head,  visual  troubles,  nervous 
troubles,  due  to  poisoning  of  the  small  capillaries  of  the  brain.  You  will 
find,  equally  independent  of  the  age,  a  cause  of  diminution  of  resistance  of  the 
kidneys  in  individuals,  due  to  the  cerebral  activity  being  dulled  by  the  use  of 
pseudo-stimulants,  such  as  morphine,  cocaine,  opium,  and  ether. 

The  same  applies  also  to  those  who  are  affected  py  gonorrhea,  syphilis,  or 
other  conditions  which  are  conveniently  called  venereal,  which  are,  all  the  more 
for  their  victims,  factors  of  moral  depression. 


AIE  SEKVIOE  MEDICAL.  127 

You  will  then  understand  the  necessity  for  you  to  have  a  renal  apparatuf< 
in  good  condition.  Imagine  to  yourselves  what  would  be  the  condition  of  a 
pilot  who  had  weak  kidney?  and  who  had  albuminuria,  when  you  know  that 
cold  is  a  serious  danger  for  this  sickness.  The  very  nature  of  the  affection 
exposes  him  to  vertigo,  muscular  cramps,  nose-bleed,  apathy,  etc.  Any  one  of 
those  ills,  insignificant  on  the  ground,  becomes  important  at  3,000  meters  in 
affecting  the  maneuvers  of  this  pilot. 

I  know  very  well  that  with  good  luck  he  would  be  able  to  right  himself  in 
time.  But  one  can  see  how,  at  times,  pilots  handicapped  by  these  affections, 
or  by  others,  may  compensate  for  these  divers  inferiorities  by  qualities  of 
accomplished  sportsmen  or  moral  qualities  of  the  first  order.  These  cases  are 
the  exceptions,  of  which  we  can  not  take  account  before  we  see  what  is  neces- 
sar>'  for  pilots  in  general. 

Let  us  look  now  to  the  respiratory  apparatus.  It  is  necessary  to  have  good 
lungs  to  be  an  aviator.  It  is  evident  that  this  increases  very  much  the  capacity 
of  resistance  of  the  organism.  Nevertheless  one  knows  aviators  of  the  greatest 
merit  who  are  very  poorly  equipped  in  this  way.  That  does  not  prevent  them 
from  fighting  very  well  even  at  4,000  meters.  But  it  is  far  better  not  to  count 
on  that,  and  it  is  well  to  suspect  all  who  have  a  predisposition  for  hemoptysis 
from  chronic  pulmonary  congestion  or  tuberculosis  or  by  arterial  hypertension. 

As  for  the  heart,  the  question  is  once  more  categorically  defined.  It  is  neces- 
sary that  the  blood  be  regularly  brought  to  the  different  parts  of  the  body  in 
order  to  nourish  it,  and  to  maintain  it  constantly  at  the  same  temperature,  if 
one  wishes  that  the  individual  should  not  suffer  too  much  from  difference  in 
pressure  in  mounting  or  descending. 

Auscultation  of  the  heart,  in  very  careful  manner,  is  of  the  utmost  importance. 
The  blood  pressure,  systolic  and  diastolic,  should  be  taken,  and  the  pulse  pres- 
sure— the  normal  relation  between  these  three — established. 

In  a  general  way,  the  practice  of  aviation  tends  to  produce  9.  lowering  of  the 
blood  pressure,  particularly  of  the  maximum  pressure,  the  minimum  pressure 
remaining  normal.  This  lowering  is  especially  appreciated  in  subjects  who  are 
slightly  or  partially  trained.  Continued  driving,  even  in  one  very  well  accus- 
tomed, may  produce  a  marked  lowering  of  arterial  pressure.  As  this  hypo- 
tension affects  at  the  same  time  both  the  maximum  and  the  minimum,  and 
in  that  it  tends  to  persist,  there  is  indicated,  further  clinical  investigation  as 
to  the  origin  of  these  manifestations.  A\'itliout  wishing  to  draw  hasty  and 
questionable  conclusions,  I  will  say  that  among  scholars  who  have  been  dis- 
charged, the  greater  part  owe  their  professional  inaptitude  to  modifications  of 
arterial  pressure. 

Note,  in  passing,  that  all  the  causes  of  raising  from  lower  to  higher  blood 
pressure,  such  as  excessive  eating,  alcoholism,  tobacco,  women,  which  lead 
to  organic  loss  of  equilibrium,  show  themselves  by  lack  of  adjustment  to 
external  conditions.  In  Paris,  in  one  of  the  halls  of  the  Grand  Palais,  there  is 
a  collection  of  interesting  experiences  on  the  inaptitude  of  candidates  who  are 
piloting  aeroplanes,  experiences  some  of  which  you  certainly  have  heard. 

This  bureau  is  under  the  direction  of  Dr.  Nepper,  a  distinguished  physiolo- 
gist. He  has  studied  with  the  aid  of  the  graphic  method  the  influence  of 
emotions  on  the  circulatory  and  respiratory  rhythm  rates. 

In  my  opinion,  it  is  not  necessary  to  draw  from  this  examination  too 
definite  conclusions,  when  it  is  a  question  of  measuring  the  intensity  of  emo- 
tional reactions  of  the  subject.  On  the  other  hand,  there  is  another  series  of 
experiences  which  to  my  mind  is  extremely  important.  It  consists  of  calcu- 
lating by  the  use  of  a  very  exact  electrical  chronometer  (d'Arsonval)  the 
reaction  time  of  the  individual  to  visual,  auditory,  and  tactile  Impressions, 
89118—19 9 


128  AIE  SERVICE  MEDICAL. 

With  a  normal  individual  this  time  is  about  .14  of  a  second  for  tactile  and  audi- 
tory impressions,  .19  of  a  second  for  visual  impressions.  (I  will  remark  in  pass- 
ing that  the  time  necessary  to  produce  a  voluntary  movement  of  adaptation  of 
defense  is  too  slow  for  visual  impressions.) 

It  has  been  observed  thus  that  the  nervous,  inattentive,  or  ill-balanced 
individual  reacts  in  a  variable  fashion,  and  it  is  exactly  on  this  proper  means 
of  reaction  time  that  one  judges  the  aptitude  of  the  aviator,  in  accordance 
with  how  this  mark  approaches  or  varies  from  unity. 

This  fashion  of  judging  candidates  by  two  methods  is  excellent ;  it  is  partic- 
ularly valuable  for  controlling  other  methods  of  examination,  and  of  fixing  for 
us  doubtful  cases. 

Let  us  now  take  the  question  of  sight,  which  is  still  under  dispute  at  the 
present  time.  It  is  better  in  principle  not  to  have  a  vision  corrected  by  glasses. 
The  aviator  needs  perfect  vision,  and  a  perfect  ability  to  distinguish  colors, 
and  a  rapid  appreciation  of  distances,  and  tlie  faculty  of  accommodating  rapidly. 
I  have  been  informed  of  many  accidents  that  are  due  to  hyperopia,  myopia, 
astigmatism;  in  other  words,  to  anomalies  in  vision.  Tlie  same  thing  holds 
for  hearing.  Both  the  middle  and  the  internal  ear  should  be  intact.  The 
changes  of  increased  pressure  and  diminished  pressure  in  the  air  and  blood 
make  themselves  very  strongly  felt  in  sclerotic  ears,  because  their  tissues  have 
lost  their  elasticity,  which  renders  these  effects  transitory. 

In  other  words,  how  can  the  pilot  get  information  of  the  changes  of  the 
rhythm  of  his  motor,  or  of  the  whizzing  of  the  air  on  the  piano  wires  of  the 
machine,  if  his  hearing  misinforms  him?  How  can  he  have  perfect  equilibrium 
in  the  air  if  he  has  an  alteration  of  the  semicircular  canals  in  the  internal  ear, 
which  are  in  such  intimate  relation  with  the  cerebellum,  the  nerve  center  of 
equilibrium?  The  slightest  affection  of  these  predisposes  to  vertigo  of  a  path- 
ological character. 

One  portion  of- the  examination  which  has  been  too  much  neglected  up  to 
yevi  recent  times  is  that  of  tho  nasal  passages.  It  is  important  that  they 
be  in  a  perfect  condition,  not  only  to  allow  to  the  pilot  easy  respiration,  but, 
even  more,  to  give  him  a  clear  perception  of  smells.  Outside  of  vision  and 
hearing  and  smell  there  should  exist  also  in  the  aviator  a  special  sense  which 
I  might  call  the  sense  of  flight,  which  may  be  developed,  but  which  can  not 
be  created  all  at  once.  The  proof  of  it  is  that  there  are  very  intelligent 
subjects,  men  to  whose  physical  fitness  absolutely  no  objection  could  be  made, 
who  could  never  make  more  than  passable  aviators.  A  good  pilot  should  feel 
entirely  at  ease  in  space.  He  should  be  able  to  recognize  at  once  the  slightest 
difficulties  with  his  machine  in  any  one  of  the  three  dimensions.  He  should 
possess  fundamentally  the  skill  of  command  to  reestablish  equilibrium  at 
any  instant,  just  as  a  cyclist  on  his  bicycle,  but  with  this  difference,  that 
there  exists  a  slight  space  of  time  between  the  moment  of  the  movement  of 
control  and  that  of  the  effect  produced.  It  is  necessary  then  to  correct  the 
movement  made,  and  at  that  point  is  the  delicate  matter  of  making 
the  movement  with  too  much  intensity,  or.  on  tbe  other  hand,  insufficient  in- 
tensity. 

In  a  word,  it  is  the  instantaneous  transformation  of  a  passing  sensation  to 
precise  muscular  contractions,  but  of  infinite  variability,  with  the  purpose  of 
constantly  reacting  to  the  invisible  movements  of  the  atmosphere  and  with 
all  the  other  difficulties  which  may  occur.  This  capacity,  as  it  seems  to  me,  is, 
above  all,  the  result  of  training.  Repetition  of  the  same  movement  results  in 
the  formation  of  a  nervous  center  which  commands  all  the  muscles  involved 
in  the  execution  of  those  movements,  and  then  of  centers  in  the  medulla,  which 


AIR  SERVICE  MEDICAL.  129 

become  substituted  for  the  brain,  in  a  transformation  of  a  sensation  to  a  move- 
ment.   This  is  the  theory  of  reflexes. 

The  formation  of  these  reflexes  varies  with  the  temperament  of  each  per- 
son. The  rapidity  of  acquiring  them  constitutes  what  is  called  aptitude.  But  In 
so  far  as  the  pilot  does  not  acquire  this  automatic  feature  of  his  movements,  he 
will  have  to  furnish  in  his  work  a  sustaining  effort  of  attention,  a  great  effort 
of  will,  which  may  go  so  far  as  producing  nervous  fatigue. 

It  remains  for  me  still  to  mention,  amid  the  clauses  which  may  modify  the 
degree  of  aptitude,  impressionability.  Scholars  have  been  seen  who  were 
victims  of  slight  falls,  who  could  not  continue  their  apprenticeship  as  they 
were  haunted  by  apprehensions  of  other  accidents.  They  are  accused  of  moral 
wealmess.  Very  often  there  is  a  correlation  between  this  moral  and  physical 
state  in  such  a  way  that  the  subjects  of  whom  I  speal<  have  been  victims  of  a 
nervous  disturbance  when  taking  a  flight. 

On  the  other  hand,  pilots  who  have  been  able  to  continue  their  training 
after  slight  or  severe  accidents  have  developed  a  coolness  and  benefited  from 
their  experiences.  They  have  learned  what  it  cost  not  to  take  sufficient  account 
of  the  council  of  their  teachers,  and  they  think  better  of  what  they  are  doing 
and  are  more  prudent.  I  do  not  mean  to  say  that  all  have  falls,  but  rather  they 
have  drawn  conclusions  from  those  that  they  have  seen.  They  generally  owe 
their  improvement  to  the  spirit  of  observation.  They  have  noticed  all  the 
causes  of  failures,  and  they  know  how  they  should  carry  themselves,  not  only 
in  their  apparatus  but  also  in  the  interval  between  flights.  And  it  is  men  of  that 
type  who  are  best  able  to  accept  the  advice  on  physical  and  moral  hygiene. 

in.  ,HYGIENE. 

Without  having  had  their  practical  experiences,  I  will  attempt  nevertheless 
to  indicate  to  you  certain  precautions  which  will  be  necessary  for  you  to  take 
to  maintain  your  aptitude  for  aviation,  and  to  get  the  most  possible  out  of  your 
faculties.  You  know  that  in  all  the  training  for  sports  there  is  necessitated  a 
definite  type  of  life.  Athletes,  runners,  horsemen,  even  submit  to  it,  and  with 
the  very  best  of  reasons;  therefore  you,  who  give  yourselves  to  a  new  sport, 
more  delicate  and  more  difficult  than  the  others,  must  also  do  so. 

This  necessity  of  being  careful  about  oneself  is  imposed  upon  all  without 
exception,  but  it  is  quite  evident  that  scholars,  students  recruited  among  the 
wounded  or  sick  of  the  war,  should  submit  to  it  even  more  rigorously  than 
others,  for  they  ought  not  to  lose  sight  of  the  fact  that  they  are  more  exposed 
than  healthy  individuals  to  the  dangers  of  aviation,  whether  it  be  cold,  damp- 
ness, or  diminution  of  the  proportion  of  oxygen  which  occurs  when  one  gets  to 
a  certain  height  or  when  the  respiration  is  embarrassed  by  fatigue. 

Let  us  speak  first  of  the  liygiene  of  the  aviator  on  the  ground.  The  first 
thing  that  would  be  necessary  to  him  is  great  liberty  of  spirit.  He  should  avoid 
family  attachments  and  other  liasons  too  absorbing.  He  should  accustom  him- 
self to  react  against  anxieties  and  unpleasant  conditions  of  all  sorts.  How  can 
the  pilot  be  a  complete  master  of  his  apparatus  if  he  is  distracted  in  his  mind, 
and  his  thought  is  elsewhere? 

A  second  question,  none  the  less  important,  is  that  of  fatigue.  The  act  of 
flying  demands  a  great  expenditure  of  energj-,  as  miich  physical  as  moral.  It  is 
a  question  then  of  not  wasting  this  energy  in  between  times.  Consequently  he 
should  avoid  all  ordinary  causes  of  fatigue,  such  as  excessive  alcoholism,  to- 
bacco, cards,  or  love.  How  many  fatal  accidents  have  originated  from  for- 
getting these  prescriptions? 


130  AIR  SERVICE   MEDICAL. 

In  the  matter  of  eating,  there  is  nothing  special  to  say.  Naturally  one  needs 
carefully  prepared  food,  which  will  permit  of  proper  recuperation  of  the  ex- 
I)ended  energj'  of  the  organism.  But  it  is  also  necessary  to  avoid  excess  at  the 
table,  for  loaded  stomachs  disturb  clearness  of  thought,  precision  of  sensation, 
and  perfect  execution  of  movement. 

To  sum  up,  the  aviator,  whether  he  be  at  school  or  at  a  squadron,  needs  a 
certain  amount  of  comfort,  sufficient  hours  of  sleep,  and  a  well-regulated  life. 
The  day  that  he  suffers  from  any  illness  whatever,  if  he  has  slept  poorly,  or 
has  bad  digestion,  and  does  not  feel  himself  in  good  form,  it  is  preferable  foi- 
him  to  remain  on  the  ground  when  he  can. 

At  the  front,  it  is  not  always  possible  to  do  this.  But  at  such  a  time  one  may 
always  have  recourse  to  stimulation  with  such  tonics  as  quinine,  arsenic,  kola, 
etc.  But  so  long  as  you  are  an  apprentice,  only  fly  when  you  are  in  good  health 
and  in  perfect  possession  of  your  senses.  Thus  you  will  always  do  well  to 
have  a  certain  interval  between  your  repast  and  the  hour  of  flight,  in  order 
that  digestion  may  have  time  to  be  completed. 

I  also  call  to  your  attention  how  foolish  it  is  to  go  up  in  an  aeroplane  not 
only  in  a  condition  of  drunkenness,  but  even  in  a  state  of  excitation,  which 
may  falsify  your  sensations  and  predispose  you  to  foolish  action. 

Finally,  I  would  recommend  to  you  a  very  ordinary  thing,  but  one  which 
nevertheless  has  its  importance.  It  is  never  good  to  go  up  in  an  aex'oplane 
without  first  having  moved  one's  bowels  and  voided  the  urine,  so  as  to  avoid,  in 
(!ase  of  a  serious  fall,  the  rupture  which  may  result  in  the  intestines  or  bladder. 
The  old  adage  of  our  fathers :  "  Head  fresh,  abdomen  free,  feet  warm,"  should 
))e  observed  in  aviation  more  particularly  than  elsewhere. 

Once  in  his  apparatus,  the  pilot  should  take  account  of  the  cold  and  of  the 
moisture  of  the  air.  The  action  of  cold  on  the  organism  increases  by  stages. 
It  is  at  first  a  sensation  of  chilling  indicated  by  a  pallor  of  the  skin,  diminution 
of  the  excretion  of  the  skin,  and  by  goose  pimples  on  the  flesh.  When  the  pilot 
is  sufficiently  protected  the  phenomena  stops  here.  Other^\'ise  the  chilling 
becomes  more  accentuated,  and  one  notices  a  painful  sensation,  the  extremities^ 
become  stiff,  a  numbness  comes  on,  with  a  tendency  to  sleep. 

How  to  contend  against  this  lowering  of  tempei'ature?  At  the  very  beginning, 
the  organism  provides  itself  at  the  first  with  a  peripheral  vaso-constriction. 
then  with  an  increased  production  of  heat.  But  if  the  cold  becomes  more  in- 
tense, or  if  its  action  is  prolonged,  external  protection  becomes  necessary. 

From  the  first,  a  shelter  is  necessary,  and  the  aeroplane  constructors  have 
provided  it,  at  the  same  time  satisfying  the  laws  of  aerodynamics,  the  fuselage 
of  the  apparatus  being  covered  in  such  a  way  that  only  the  head  of  the  pilot 
emerges  from  the  hood. 

Finally,  there  is  need  of  appropriate  clothing.  Best  is  certainly  woolen 
clothing,  for  it  is  proved  that  wool  counteracts  most  advantageously  the  loss  of 
heat  which,  as  on  the  earth,  moves  by  conductivity,  radiation,  and  evaporation, 
and  especially  by  convection.  The  chilling  by  convection  is  due  to  the  circula- 
tion of  external  air,  which  rapidly  passes  even  through  the  thickest  clothing, 
chills  the  skin,  and  escapes  after  having  been  warmed.  Let  us  say  in  passing 
that  paper  lining  in  the  form  of  thin  layers  gives  greatest  amoimt  of  protec- 
tion. Flannel  applied  directly  over  the  skin  is  highly  recommended,  for  if 
regulates  evaporation.  A  woolen  sweater  is  added  to  this,  then  a  combination 
.suit,  fur-lined,  and  fur-lined  boots,  sufficiently  large  to  avoid  any  pressure  on 
the  feet  or  limbs. 

One  should  not  put  tampons  of  cotton  in  the  ears  because  they  are  useless 
and  even  dangerous  to  the  security  of  the  aviator.  You  will  remember  that  in 
ascending  the  aviator  is  relieved  in  breathing  largely  by  making  use  of  the 


ATE  SEBVICE   MEDICAL.  131 

mouth  and  by.  practicing  the  valsalva  uiaueuver,  which  consists  in  malcing  a 
blowing  effort  with  the  mouth  and  nose  closed;  and  that  in  descending  he  will 
relieve  himself  by  practicing  the  experiment  of  Toynbee,  which  consists  in 
making  a  movement  of  swallowing  after  having  closed  the  nose  and  mouth. 
The  eyes  will  be  protected  from  the  eifect  of  the  wind  and  dust  by  glasses  similar 
to  those  used  by  autoraobilists.  The  hands  should  be  coveretl  by  large  gloves, 
thickly  fur-lined  with  rabbit  skin  or  cat  fur,  for  example. 

As  for  the  head  covering,  it  will  consist  of  a  woolen  helmet  or  one  of  skin 
surmounted  by  a  helmet  of  leather  furnished  ,with  iron  strips  to  lessen  the 
shock  in  caso  of  fall.  In  passing.  I  will  recall  to  .vour  attention  that  the 
helmet  alone  suffices  in  warm  weather  to  protect  the  pilot  from  sunstroke. 

In  r6sum§,  the  costume  of  the  aviator  should  be  warm  and  sufficiently 
ample,  of  a  type  to  permit  ventilation  of  the  body  and  a  complete  liberty  of 
movement.  As  for  the  rest,  this  amplitude  Mill  only  result  in  increasing  the 
heat  by  the  insulated  layer  which  the  inclosed  air  produces. 

In  the  winter  time  one  may  add  to  this  clothing  by  utilizing  skins  of  animals, 
Maxed.  such  as  the  "  paraphiies  du  chauffeur."  which  will  have  at  the  same 
time  the  advantage  of  protecting  him  from  the  moi.sture.  This  last  is  im- 
portant, for  it  has  the  natural  consequence  of  chilling  the  body  very  rapidly, 
if  allowed  to  penetrate. 

At  times  it  happens,  on  the  other  hand,  that  the  air  is  very  dry  at  great 
elevations.  Then  the  loss  of  water,  which  takes  place  through  the  skin  and 
raucous  membrane,  may  not  be  compensated  for  sufficiently  quickly  by  the 
production  of  water  from  the  body.  As  a  result  of  this,  sensations  of  parching 
of  the  skin,  chapping,  cracking  of  the  lips,  and  the  arrest  of  the  salivary 
secretion,  dryness  of  the  throat,  develop,  produced  all  the  more  quickly  when 
the  hygrometric  conditions  have  changed  very  rapidly. 

All  these  phenomena  increase  with  elevation.  It  is  well  for  you  when  you 
make  a  high  flight  to  apply  to  your  face,  and  especially  to  the  nostrils  and 
the  lips  a  light  coating  of  ointment  such  as  cold  cream,  glycerine,  petrolatum. 
etc. 

Along  the  same  line  it  would  be  well  to  induce  a  little  vaseline  in  the  nostrils 
in  order  to  preserve  the  mucus  in  the  nose  and  pharynx.  This  last  precautioj; 
will  have  the  advantage  of  being  also  helpful  against  humidity  and  dryness. 

Finally,  I  will  make  one  last  recommendation,  that  of  taking  a  light  rest 
after  each  flight.  It  is  the  best  way  to  preserve  strength,  and  to  reinvigorate 
oneself  in  proportion.  That  will  permit  you  when  you  are  at  the  front,  to 
remain  there  much  longer  and  to  do  much  better  work  while  there. 

Doctor  Guilbekt. 
ITALIAN. 

The  best  medical  experts  of  Italy  are  in  charge  of  the  examination 
and  care  of  the  flier.  This  work  is  fully  organized  and  is  much  ap- 
preciated hj  their  Air  Service.  The  Italians  have  two  centers  at 
which  this  work  is  done.  They  have  the  most  complete  equipment 
and  every  encouragement  and  opportunity  to  do  the  highest  type  of 
work. 

■PSICHO-PHYSIOLOOIC    TMSTITTJTE, ,   ITALY.   DECEMBER    28,    1917. 

This  institute  is  in  charge  of  specialists  and  is  under  the  direction 

of  Prof.  Gradenigo.     At  present  he  is  in opening  up  another 

examining  center.     This  is  done  so  that  it  will  not  be  necessaiy  for 


132  Am  SEEVIOE  MEDICAL. 

all  applicants  to  go  to  .     The  first  thing  that  strikes  us  on 

seeing  the  Italian  medical  situation  is  that  ALL  candidates  came  from 
some  other  branch  of  military  service,  for  the  obvious  reason  that 
ALL  fit  men  are  already  in  the  service.  It  is  a  case  of  request  for 
TRANSFER  into  the  Aviation  Service. 

CANDIDATES. 

All  candidates  are  examined  here  at  this  institute.  The  present 
average  is  35  per  diem.     They  expect  soon  to  get  up  to  80,     This  is 

probably  due  to  the  anticipated  work  of  the  unit  at .     There  are 

some  of  the  military  surgeons  worlring  here,  although  these  seem  to 
be  made  up  mostly  of  those  who  were  specialists  in  civil  life,  before 
the  war.  Then  there  are  also  "  civilian  consultants.''  I  do  not  know 
whether  they  are  appointed  by  the  Government  or  by  Dr.  Gradenigo. 
They  seem,  however,  to  be  the  very  best  type  of  physicians,  and  are 
of  the  average  age  of  about  48.  They  are  of  the  dignified  "  professor  " 
sort. 

REEXAMINATION   OF  FLIERS. 

None  are  examined  again  so  long  as  they  seem  to  get  along  all 
right.  But  I  just  saw  a  man  who  had  had  a  spill,  which  had  broken 
two  ribs.     This  man  feels  all  right  and  probably  wonders  what  it  is 

all  about— but  they  have  sent  him  back  to  to  be  examined 

all  over  again.     They  reexamine  all  those  who  have  been  injured 

before  allowing  them  to  fly  again.     As  is  not  "very  far 

away  "—this  is  not  such  an  enormously  large  country — it  probably 
does  not  take  a  very  long  time  for  the  aviator  to  get  here  and  then 
get  back  to  the  front.  It  would  seem,  however,  that  if  they  could 
have  experts  also  at  the  front  that  they  could  solve  this  matter  in  a 
much  simpler  way,  by  providing  a  final  opinion  on  the  spot,  even  if 
they  had  only  one  more  unit  located  at  headquarters  at  the  front. 

SPECIAL  FEATURES  OF  THE  ITALIAN  EXAMINATION. 

They  put  great  emphasis  on  the  REACTION  TIME.  Their  tests 
;ire  veiy  simple  and  admirable.  I  was  put  through  the  tests  as  a  "can- 
didate." I  held  my  finger  pressed  down  on  a  sort  of  telegraph  key, 
and  all  I  had  to  think  about  was  that  the  instant  a  light  flashed  in 
front  of  me  I  was  to  lift  my  hand  instantly  off  the  key.  This  was 
repeated  quickly  30  times  and  recorded  on  a  watchlike  instrument. 
The  whole  thing  was  electrical  and  there  was  very  little  opportunity 
for  error  apparently ;  anyhow  there  is  no  doubt  that  frequent  experi- 
ments have  demonstrated  an  average  "normal"  time  for  this  re- 
sponse to  come  through,  and  so  when  any  man  falls  weU  below  this 
average  it  is  safe  to  say  that  he  does  not  respond  as  quickly  as  he 


AIB  SEBVIOE   MEDICAL.  133 

ought.  The  point  is  that  the  Italians  lay  stress  on  the  importance 
of  an  alert  response,  motor,  to  external  stimuli.  They  disqualify 
about  2  per  cent  of  the  men  by  their  failure  in  this  test  alone.  If  a 
man  is  perfectly'  normal  in  his  entire  mechanism  and  yet  does  not 
show  that  he  is  "  quick  on  the  trigger,"  he  is  considered  unfit  to  be 
a  flier. 

OBSERVATIONS  MADE  DECEMBER  29,  1917. 

A  full  day  spent  in  going  through  all  tjie  Italian  tests  in  detail. 

ESSENTIAL  POINTS. 

They  record  many  of  their  tests  on  revolving  drums.  The  test  of 
the  emotions  is  particularly  striking.  Rubber  tubes  are  adjusted,  one 
to  a  double  pad  over  the  region  of  the  common  carotids,  another  over 
the  chest,  another  over  the  right  hand,  and  another  to  a  glass  tube  in 
which  the  left,  forearm  is  inserted,  and  then  the  tube  filled  with 
water.  The  drum  starts  to  revolve.  The  needles  record  the  pulse  of 
the  carotids,  the  respiration,  whether  there  is  any  tremor  of  the  right 
hand,  and  the  level  of  the  vasomotor  tone  in  the  left  forearm.  Sud- 
denly a  bomb  is  exploded  directly  behind  the  man,  by  throwing  it  on 
the  floor  under  him.  All  the  needles  take  a  sudden  jump.  The  man 
I  saw  showed,  however,  an  immediate  return  of  all  the  needles  to 
their  original  amplitude  and  level  of  the  line — that  is  to  say,  the 
tracings  after  the  explosion  were  just  the  same  as  before.  This 
showed  that  he  had  a  normal  involuntary  "  start "  when  the  bomb  went 
off.  but  that  it  did  not  disturb  him  because  his  heart-beat,  his  respira- 
tions, steadiness  of  the  right  hand,  and  vasomotor  tension  in  the 
left  forearm  showed  immediate  recovery.  Other  tracings  of  others 
examined  showed  that  these  functions  did  not  recover,  but  were 
"  all  shot  to  pieces  ";  the  pulse  would  be  verj'^  rapid,  also  respirations, 
the  right  hand  would  tremble  and  the  vasomotor  tension  line 
dropped — showing  that  the  peripheral  tension  had  diminished — evi- 
dence of  shock.    This  latter  type  is  disqualified. 

The  Italians  even  go  so  far  as  to  take  a  tracing  of  the  degree  of 
nasal  stenosis.  A  catheter  is  put  in  the  right  naris  all  the  way  back. 
Man  breathes,  then  cotton  is  put  in  the  left  naris.  If  the  tracing 
shows  no  increase,  it  is  evidence  that  the  left  naris  is  stenosed.  They 
hitch  up  the  tube  to  a  sort  of  barometric  tube  and  measure  the  degree 
of  stenosis.  To  me,  this  seems  ver^^  "  fancy  "  and  entirely  unneces- 
sary, as  it  is  a  very  simple  matter  to  see  what  is  the  condition  of  a 
man's  nares.  However,  it  must  be  noted  that  the  Italians  do  not  put 
all  the  candidates  through  the  tests.  It  depends  on  how  much  time 
they  have.  Also  on  special  cases  they  have  all  these  data  to  help 
them. 


134  AIB  SEBVIOE  MEDIOAL. 

They  have  a  VACUUM  CHAMBER.  Many  experiments  have  been 
made  in  it  during  the  past  dozen  years  or  more.  (We  have  in  our  pos- 
session reprints  which  they  gave  me,  written  in  French.)  They  feel 
that;  1.  Oxygen  is  not  necessary  for  fliers.  2.  If  given,  it  should 
not  be  pure  oxygen,  but  oxygen  90  per  cent,  carbon  dioxide  10  per 
cent. 

This  enabled  them  to  take  their  famous  ourang-outang  much 
higher  than  he  could  go  with  pure  oxygen  alone.  They  also  have 
made  tests  on  human  beings  with  the  same  results  and  conclusions. 
They  did  not  feel  that  the  present  heights  attained  in  flying  required 
OXYGEN,  and  were  very  definite  in  their  statement  that  no  pro- 
fessors had  done  as  much  work  on  this  subject  as  they  had  done  here 
in  Italy,  and  that  there  was  no  room  for  argument.  (So  I  did  not 
open  any  argument.) 

The  Carlinga  is  the  piece  de  resistance.  It  is  a  regular  aeroplane 
seat  and  body. 

TESTS. 

1.  Man  blindfolded. — They  move  the  outfit,  man  and  all,  to  a  cer- 
tain inclination.  Then  he  indicates  with  a  pointer  what  he  considers 
to  be  the  exact  perpendicular.    This  error  is  read  off  on  a  scale. 

2.  Eyes  open. — He  takes  hold  of  the  joy  stick.  They  move  the  out- 
fit ajid  he  moves  the  stick  to  compensate.  There  is  a  sj'stem  of  elec- 
tric lights  connected  with  this  test,  to  determine  if  he  is  accurate. 
They  have  electrical  connections  with  the  under  end  of  the  joy 
stick,  and  when  he  presses  it  in  a  certain  direction  those  particular 
lights  flash.  There  are  three  sets  of  lights,  one  set  for  lateral  move- 
ment, one  for  sagittal — both  controlled  by  the  joy  stick — and  one  set 
foi-  horizontal  movement  controlled,  as  in  a  plane,  by  the  foot  rudder. 

This  test  is  obviously  along  entirely  original  lines.  It  consti- 
tutes the  test  for  the  reaction  time  to  the  detection  of  movement. 
Just  as  the  reaction  time  has  been  tested  for  the  sense  of  sight,  the 
sense  of  hearing,  and  the  sense  of  touch,  so  by  means  of  the  Carlinga 
it  is  possible  to  determine  the  reaction  time  to  a  stimulation  of  the 
vestibular  mechanism  and  deep  sensibility. 

They  place  a  prime  importance  on  the  mechanism  vestibulaire. 
They  would  not  think  of  accepting  a  man  whose  ear  mechanism  was 
not  good.  And  yet  all  they  do  in  the  tuniing-chair  is  to  turn,  with 
EYES  OPEN,  and  see  if  he  has  a  good  nystagmus.  Say  that  between 
25  and  35  is  normal.  This  exactly  agrees  with  our  figures  as  we 
test,  eyes  straight  ahead,  and  they  with  eyes  in  the  extreme  position 
opposite  endolymph  movement.  This  w^ould  normally  increase  the 
length  somewhat.  They  were  much  interested  in  our  methods,  and 
had  a  copy  of  it  in  Italian.  They  asked  me  to  demonstrate  our 
method.    They  had  no  suitable  head-rest  and  let  the  head  go  in  any 


AIB   SERVICE   MEDICAL.  135 

position;  also  they  had  no  stop-pedal  and  were  a  little  uncertain  of 
meaning  of  past-pointing.  They  knew  what  I  meant,  but  did  not 
seem  to  see  that  it  had  anything  especially  to  do  with  the  aviator. 
They  made  no  mention  of  the  use  of  the  caloric  test. 

Their  general  physicals  are  well  done,  but  nothing  of  interest. 

Eye  work  beautifully  done,  and  the  in.^truments  very  fine.  Every 
man  has  the  test  for  vision  "  at  night."  This  is  done  in  a  dark  room 
and  estimation  made  in  two  ways:  (1)  A  light  is  moved  further  and 
further  away  from  the  card;  (2)  cards  are  of  varying  backgrounds, 
becoming  darker  and  darker. 

VISIT  TO  PROF.    (LIEUT.   COL.)    GltADEMlGO,   ITALY,   JANUARY    5,    1918. 

The  professor  says  that  the  great  need  is  that  the  doctors  concerned 
in  the  matters  of  aviation  should  get  together  and  learn  from  each 
other.  He  volunteered  the  idea  that  all  the  tests  of  all  the  countries 
should,  as  far  as  possible,  be  the  same.  The  objections  to  this  are 
that  the  number  and  type  of  candidates  in  these  different  countries 
vary  so  greatly.  He  is.  however,  in  complete  accord  with  the  value 
of  knowing  each  other's  ideas.  He  will,  in  the  immediate  future, 
cooperate  in  any  plan  that  is  presented  to  bring  about  an  interchange 
of  ideas.  He  urged  that  we  send  our  men  from to  be  exam- 
ined by  them  here.    He  put  it  rather  in  this  way : 

We,  the  Italians,  are  at  your  service  to  examine  any  of  your  men  for  you 
at  any  time.    Also  that  a  comparison  of  the  findings  of  the  examination  might 

be  helpful.     This  new  unit  at  will  be  in  good  working  order  in  a  few 

weeks,  although  it  will  be  a  couple  of  mouths  before  it  is  equal  to . 

We  have  in  our  possession  the  examination  blanks  used  by  the 
Italian,  service.  Each  special  department  has  its  own  blank.  After 
these  are  all  filled,  another  blank  is  used  by  the  medical  officer  in 
charge,  who  makes  a  brief  summary  of  the  results  of  the  detailed 
examinations  given  in  the  various  blanks.  The  Italians  also  fur- 
nished us  with  many  photographs  of  their  apparatus  and  methods 
of  examination,   also   data   bearing  especially   upon  the   elaborate 

studies  which  have  been  conducted  by  the  University  at  for 

many  years,  upon  the  effects  of  high  altitudes  upon  human  beings 
and  ourang-outangs. 

We  explained  that  our  standards  were  very  simple  and  definite 
because  of  our  67  units  and  the  need  of  standardizing  the  work  at 
all  these  places.  The  main  suggestion  that  we  have  learned  from  the 
Italians  is  that  we  might  do  well  to  make  a  routine  t^st  of  the 
REACTION  TIME.  They  consider  it  very  important.  It  would, 
however,  be  very  difficult  to  apply  it  in  any  standard  way  for  so 
many  units. 

The  Italians  are  eager  to  join  us  in  any  effort  to  help  "  the  cause  "; 
namely,  the  "SPECIAL  MEDICAL  CARE  OF  THE  AVIATOR." 


CHAPTEK  VII. 
MANUAL  OF  THE  MEDICAL  RESEARCH  LABORATORY. 

I.— ALTITUDE  PHYSIOLOGY. 

In  recent  years  our  knowledge  of  the  conditions  pertaining  to  life 
at  high  altitudes  has  been  enriched  b}^  careful  scientific  investiga- 
tions. The  majority  of  these  have  been  carried  out  on  Monte  Rosa 
in  Europe  and  on  Pike's  Peak  in  the  United  States.  Further  con- 
tributions come  from  studies  made  in  pneumatic  cabinets  in  which 
the  atmospheric  pressure  can  be  reduced  to  any  degree  correspond- 
ing to  known  heights. 

The  physiologic  effects  of  altitude  on  man  and  other  animals  have 
a  threefold  interest.  The  purely  scientific  aspects  of  the  life  under 
conditions  of  low  barometric  pressure  are  themselves  deserving  of 
careful  investigation.  The  fact  that  altitude  plays  a  part  in  thera- 
peutics and  forms  a  feature  of  climatology,  as  applied  by  medicine, 
furnishes  another  reason  why  the  subject  should  be  placed  on  a  ra- 
tional basis.  While  the  coming  into  prominence  of  aviation  which 
requires  a  man  to  ascend  into  the  air  as  the  bird,  frequently  to  mod- 
erate and  sometimes  to  great  altitudes,  furnishes  a  third  reason  why 
we  should  know  what  constitutes  fitness  for  life  in  rarefied  air.  As 
soon  as  an  attempt  is  made  to  interpret  the  physiologic  phenomena 
of  altitude  in  terms  of  their  causes  difiiculties  arise.  The  reason  for 
contradictory  theories  is  to  be  found  in  the  complexity  of  the  factors 
which  enter  into  the  environment  at  high  altitudes.  Among  the  cli- 
matic variables  are  the  low  atmospheric  pressure  with  its  low  partial 
pressure  of  oxygen,  the  peculiarities  of  the  sunshine,  low  temperature 
and  humidity,  the  high  wind,  the  electric  conditions  of  the  atmo- 
sphere, and  ionization.  It  has  been  found  difficult  to  study  these  fac- 
tors one  at  a  time,  but  with  the  use  of  the  pneumatic  cabinet  it  is 
possible  to  eliminate  all  factors  except  lowered  barometric  pressure 
and  also  to  study  the  added  influence  of  other  altitude  factors.  The 
consensus  of  opinion  held  is  that  the  physiologic  effects  noted  at  high 
altitudes  are  due  to  the  lack  of  oxygen  resulting  from  the  lowered 
partial  pressure  of  oxygen. 

It  is  clearly  established  to-day  that  high  altitudes  or  low  baro- 
metric pressure  when  first  encountered  may  interfere  with  the  normal 
workings  of  the  human  machine.  A  sudden  disturbance  of  any  sort 
of  the  bodily  functions  is  usually  manifest  by  symptons  of  illness. 

187 


138  AIB  SEBVIOE  MBMOAL. 

Those  disturbances  brought  on  by  change  of  altitude  cause  the  so- 
called  mountain  sickness,  or,  better,  altitude  sickness,  the  symptoms 
of  which  are  generally  so  mild  that  they  may  be  entirely  overlooked 
by  the  unobservant.  Mankind  differs  greatly  in  the  power  of  ad- 
justment to  changes  of  environment.  Hence,  it  is  found  that  moun- 
tain sickness  befalls  some  individuals  at  a  lower,  others  at  a  higher 
altitude,  but  it  is  also  certain  that  no  one  who  proceeds  beyond  a 
certain  elevation — the  critical  line  for  him — escapes  the  malady.  An 
elevation  of  10,000  feet  or  even  less  might  provoke  it  in  some,  others 
may  escape  the  symptoms  up  to  14,000  feet,  while  only  a  very  few. 
possessed  of  unusual  resisting  poAver,  can  without  much  distress 
venture  upward  to  19,000  feet.  The  symptoms  of  mountain  sickness 
depend  not  only  on  the  nature  of  the  individual  and  his  physical 
condition,  but  also  on  various  intricate  contingencies,  especially  on 
the  amount  of  physical  exertion  made  in  ascending;  that  is,  on 
Avhether  the  ascent  is  performed  by  climbing  or  b^'^  passive  carriage 
on  horse,  on  railway  train,  or  in  an  aeroplane. 

There  are  two  forms  of  mountain  sickness;  the  acute  and  the  slow. 
The  acute,  due  to  going  too  far  beyond  the  individual  critical  line, 
breaks  out  suddenly  on  entrance  into  the  rarefied  air;  the  slow  mani- 
fests itself  later  and  other  debilitating  causes  besides  the  barometric 
depression  often  contribute  to  produce  it. 

The  acute  form  is  characterized  by  a  rapid  pulse,  nausea,  vomiting, 
phj'sical  prostration  which  may  even  incapacitate  one  for  movement, 
livid  color  of  the  skin,  buzzing  in  the  ears,  dimmed  sight,  and  faint- 
ing fits. 

In  the  slow  form  of  mountain  sickness,  which  may  be  called  the 
normal  type,  the  newcomer  at  first  complains  of  no  sj^mptoms.  In 
fact,  when  questioned  he  says  he  feels  fine.  Occasionally  he  may 
report  that  on  stooping  over  and  raising  himself  up  again,  he  feels 
dizzy  and  has  a  visual  sensation  of  blackness.  Even  at  this  time  on  ex- 
amination there  is  found  blueness  of  the  lips,  edges  of  the  eyelids, 
gums,  and  under  the  finger  nails.  Some  houi*s  later  he  begins  to 
feel  "good  for  nothing"  and  disinclined  for  exertion;  to  express  it 
differently,  he  finds  that  he  feels  somewhat  weak  and  exhausted. 
He  goes  to  bed  and  has  a  restless  and  troubled  night  and  wakes  up 
next  morning  with  a  severe  frontal  headache.  Many  find  that  the 
headache  begins  to  develop  toward  evening  or  during  the  night  of 
the  first  day.  Following  it  there  may  be  vomiting  and  frequently  a 
sense  of  depression  in  the  chest.  The  patient  may  feel  slightly  giddy 
on  arising  from  bed  and  any  attempt  at  exertion  increases  the  head- 
ache which  is  nearly  always  confined  to  the  frontal  region.  On 
exammation  the  face  may  be  slightly  cyanosed,  the  eyes  look  dull 
and  heavy  and  there  may  be  a  tendency  for  them  to  water.  The 
t,ongue  is  furred,  the  pulse  is  nearly  always  high,  being  generally  in 


AIB   SERVICE   MEDICAL.  139 

the  neighborhood  of  100  or  over.  The  temperature  is  normal  or 
slightly  under.  The  patient  often  feels  cold  and  shivery.  All  ap- 
petite is  lost,  some  have  diarrlioea  and  abdominal  pain.  A  tendency 
to  periodic  breathing  is  observed  in  many  and  physical  exertion  is 
accompanied  by  great  hyperpnoea. 

There  are  wide  divergencies  from  this  slow  or  normal  type  of 
mountain  sickness.  Dr.  Ravenhill  has  grouped  these  into  two  classes, 
(1)  those  in  which  cardiac  symptoms,  and  (2)  those  in  which  nerv- 
ous symptoms  predominate.  Neither  is  common.  The  cardiac  type 
is  well  illustrated  by  one  of  Dr.  Ravenhill's  cases.  An  English 
gentleman  in  the  Andes  Mountains  ascended  from  sea  level  to  15,400 
feet  in  42  hours.  Three  years  before  he  had  lived  at  the  same  alti- 
tude for  a  period  of  three  months  and  had  been  in  good  health  the 
whole  time.  He  seemed  in  good  health  upon  arrival ;  he  kept  quiet, 
ate  sparingly,  and  went  to  bed  early,  but  awoke  the  next  morning 
feeling  ill  with  symptoms  of  the  normal  type.  Later  in  the  da}'^  he 
began  to  feel  very  ill.  In  the  afternoon  his  pulse  rate  was  144, 
respirations  40.  Later  in  the  evening  he  became  very  cyanosed,  had 
acute  dyspnoea  and  evident  air  hunger,  all  the  extraordinary  mus- 
cles of  respiration  being  called  into  play.  His  heart  sounds  were 
very  faint;  the  pulse  irregular  and  of  small  tension,  thus  presenting 
a  typical  picture  of  a  failing  heart.  The  condition  persisted  during 
the  night:  he  coughed  up  with  difficulty  and  vomited  at  intervals. 
He  was  sent  down  on  an  earl}'  train  the  next  morning.  At  12,000 
feet  he  was  considerably  better  and  at  7,000  feet  he  was  nearly  well. 
Dr.  Ravenhill  thought  that  he  would  have  died  had  he  remained 
another  day. 

The  nervous  type  of  mountain  sickness  in  its  simplest  form  con- 
sists of  the  feeling  of  a  nervous  excitation  and  buoyancy.  Some 
feel  as  though  they  are  being  lifted  into  the  air  as  by  a  balloon. 
There  may  be  a  tendency  to  twitching  of  the  lips  and  trembling  of 
the  limbs.  In  severe  cases  these  may  lead  on  to  violent  spasmodic 
movements  of  the  limbs  and  even  convulsions.  Vertigo  may  be  a 
prominent  symptom,  though  it  is  very  rarely  pronounced. 

The  symptoms  of  mountain  siclaiess  persist  for  one,  two,  and  three 
days  and  then  gradually  disappear  as  the  adaptive  reactions  to  high 
altitude  occur.  The  action  of  gi'adually  developing  want  of  oxygen 
at  very  high  altitudes  is  very  insidious  as  dangerous  effects  may 
develop  with  a  dramatic  suddenness.  Two  now  historic  experiences 
illustrate  this.  In  1862  the  Avell  known  meteorologist,  Glaisher,  and 
his  assistant,  Coxwell,  ascended  in  a  balloon.  Glaisher  first  noticed 
at  an  altitude  of  about  26,000  feet  that  he  could  not  read  his  instru- 
ment properly.  Shortly  after  this  his  legs  were  paralyzed  and  then 
his  arms,  though  he  could  still  moA'e  his  head.  Then  his  sight  failed 
entirely  and  afterwards  his  hearing  and  he  became  unconscious.     His 


140  AIR  SEEVIOE  MEDICAL. 

companion  meanwhile  found  that  liis  arms  were  paralyzed,  but  that 
he  was  still  able  to  seize  and  pull  the  rope  of  a  valve  with  his  teeth — 
this  permitted  gas  to  escape — so  that  the  balloon  descended.  As 
Glaisher  recovered  consciousness,  he  first  heard  his  companion's  voice 
and  then  was  able  to  see  him,  after  which  he  quickly  recovered.  The 
balloon,  during  the  ascent,  reached  an  altitude  of  about  30,000  feet. 
The  second  of  these  historic  experiences  is  found  in  a  gi'aphic  account 
given  by  Tissandier,  the  sole  survivor  of  a  party  of  three  in  a  fatal 
balloon  ascent  in  1875. 

"  I  now  come  to  the  fateful  moments  when  we  were  overcome  by  the  terrible 
action  of  reduced  pressure.  At  22,900  feet  (320  mm.)  we  were  all  below  iu 
the  car — torpor  had  seized  me.  My  hands  were  cold  and  I  wished  to  put  on 
my  fur  gloves;  but,  without  my  being  aware  of  it,  the  action  of  taking  them 
from  my  pocket  required  an  effort  which  I  was  unable  to  make.  At  this  height 
I  wrote,  nevertheless,  in  my  notebook  almost  mechanically  and  reproduce  liter- 
ally the  following  words  though  I  have  no  very  clear  recollection  of  writing 
them.  They  are  written  veiy  illegibly  by  a  hand  rendered  very  shaky  by  the 
cold :  "  My  hands  are  frozen.  I  am  well.  We  ai*e  well.  Haze  on  the  horizon, 
with  small  round  cirrus.  We  are  rising.  Croc6  is  panting.  We  breathe 
oxygen.  Sivel  shuts  his  eyes.  Croc§  also  shuts  his  eyes.  I  empty  aspirator, 
1.20  p.  m..  — 7  to  — 11  degrees,  barometer  320.  Sivel  is  dozing,  1.25,  — 11 
degrees,  barometer  300.  Sivel  throws  ballast  (last  word  scarcely  legible)." 
I  had  taken  care  to  keep  absolutely  still  without  suspecting  that  I  had  already 
perhaps  lost  the  use  of  my  limbs.  At  24,600  feet  the  condition  of  torpor  which 
overcomes  one  is  extraordinary.  Body  and  mind  become  feebler  little  by 
little,  gradually  and  insensibly.  There  is  no  suffering.  On  the  contrary  one 
feels  an  inward  joy.  There  is  no  thought  of  the  dangerous  position ;  one  rises 
and  is  glad  to  be  rising.  The  vertigo  of  high  altitude  is  not  an  empty  word ; 
but  so  far  as  I  can  judge  from  my  own  impressions  this  vertigo  appears  at  the 
last  moment,  and  immediately  precedes  extinction,  sudden,  unexpected,  and 
irresistible.  I  soon  felt  myself  so  weak  that  I  could  not  even  turn  my  head  to 
look  at  my  companions.  I  wished  to  take  hold  of  the  oxygen  tube  but  found 
that  I  could  not  move  my  arms.  My  mind  was  still  clear,  however,  and  I 
watched  my  aneroid  with  my  eyes  fixed  on  the  needles  which  soon  pointed  to 
290  mm.  and  then  to  280.  I  wished  to  call  that  we  are  now  at  26.000  feet, 
but  my  tongue  was  paralyzed.  All  at  once  I  shut  my  eyes  and  fell  down  power- 
less and  lost  all  further  memory.    It  was  about  1.30." 

The  balloon  ascended  28,820  feet  and  then  descended.  Tissandier 
recovered  but  his  companions  lost  their  lives  in  the  ascent.  These 
extreme  cases  are  cited  here  in  order  to  bring  to  the  attention  of 
aviators  the  risk  in  going  to  extremely  high  altitudes  without  oxygen. 

THE   CAUSE   OF  THE   SYHIPTOMS  OF   MOUNTAUST   SICKNESS. 

The  essential  cause  of  altitude  sickness  is  lack  of  oxygen.  The 
probability  of  this  explanation  was  first  clearly  pointed  out  by 
Jourdanet,  but  it  was  Paul  Bert,  in  1878,  who  first  furnished  clear 
experimental  proof  that  the  abnormal  symptoms  and  dangers  depend 
on  the  imperfect  aeration  of  the  arterial  blood  with  oxygen.     He 


AIR   SERVICE   MEDICAL.  141 

concluded  that  all  the  symptoms  are  simply  those  of  want  of  oxygen. 
Later  observers,  however,  questioned  this  conclusion  and  attributed 
the  symptoms  in  whole  or  in  part  to  other  causes.  Mosso  attributed 
many  of  the  symptoms  to  the  lack  of  carbon  dioxide,  while  Kronecker 
has  invoked  mechanical  factors  as  a  cause.  The  evidence  accumu- 
lated by  more  recent  workers,  both  on  mountains  and  in  pneumatic 
chambers,  have  definitely  confirmed  Paul  Bert's  conclusion. 

The  call  for  oxygen  in  the  body  comes  from  the  active  cells  of  the 
tissues.  It  has  been  evident  for  sometime  that  the  place  of  oxida- 
tion is  in  the  ceils  and  not  in  the  blood  as  was  formerly  maintained. 
Complete  deprivation  of  oxygen  results  in  asphyxiation  and  death. 
The  question  that  naturally  arises  is ;  Is  the  quantity  of  oxygen  taken 
up  by  the  cell,  conditioned  primarily  by  the  needs  of  the  cell  or  by 
the  supply  of  oxygen  ?  This  has  been  answered  clearly ;  the  cell  takes 
what  it  needs  and  leaves  the  rest.  Therefore,  it  is  important  that 
sufficient  oxygen  be  available  in  the  blood  when  the  demand  is  made 
by  the  tissues.  The  rate  of  flow  and  the  amount  of  oxygen  passing 
from  the  blood  to  the  tissues  depends  on  the  difference  between  the 
pressure  of  oxygen  in  the  blood  and  in  the  tissue.  The  higher  the 
oxygen  pressure  in  the  blood  the  greater  will  be  the  amount  of 
oxygen  passing  from  the  blood  of  the  capillaries  into  the  tissues  in  a 
given  unit  of  time.  Oxygen  diffuses  from  the  place  of  higher  pres- 
sure to  the  place  of  no  pressure  or  low  pressure.  In  the  active  tis- 
sues the  oxygen  tension  is  always  low  and  it  is  usually  supposed 
there  is  then  no  oxygen  pressure  at  all  inside  the  cells.  The  dissocia- 
tion of  oxygen  from  the  hemoglobin  of  the  blood  occurs  with  great 
rapidity,  but  it  is  greatest  where  the  differences  in  pressure  are 
greatest.  It  follows,  therefore,  that  the  oxygen  pressure  in  the  blood 
must  be  sufficiently  high  to  supply  the  needs  of  the  cell  in  the  brief 
interval  of  time  that  the  blood  is  passing  through  the  capillaries. 

There  are  many  ways  in  which  the  oxygen  supply  of  the  body  may 
be  reduced.  Wliatever  the  method  used  there  will  occur  compensa- 
tory adaptive  reactions  in  the  blood,  the  breathing,  and  the  circula- 
tion for  the  purpose  of  furnishing  the  oxygen  needed  by  the  cell. 
Reduction  of  oxygen  available  to  the  tissues  might  be  brought  about 
by  blood  letting  and  anemia ;  by  the  administration  of  carbon  monox- 
ide or  sodium  cyanide;  by  life  on  high  moimtains,  in  a  balloon,  in  an 
aeroplane  at  high  altitudes,  or  in  pneumatic  cabinets  at  reduced 
pressure ;  by  the  artificial  restriction  of  the  free  influx  of  atmospheric 
air  into  the  lungs;  and  by  artificial  pneumothorax.  Any  of  these 
methods,  if  carried  bej^ond  a  certain  point,  is  known  to  produce 
death.  If,  on  the  other  hand,  they  are  only  carried  far  enough  to 
give  a  mild  oxygen  hunger,  the  body  will,  as  a  rule,  react  so  as  to' 
compensate  for  the  reduction  in  the  oxygen  supply. 


142  AIR  SERVICE   MEDICAL. 

In  blood  letting,  which  produces  an  artificial  anemia,  the  percent- 
age of  oxygen  in  the  venous  blood  may  be  reduced  from  the  normal 
12  volumes  per  cent  to  4  or  even  3  per  cent.  In  animals  thus  treated 
both  the  circulation  and  the  breathing  Avill  show  compensatory  activ- 
ity. In  cases  of  anemia  with  a  20  per  cent  reduction  in  hemoglobin 
an  increased  pulse  rate  and  an  increased  respiration  will  be  observed. 
In  cases  of  poisoning  with  carbon  monoxide  and  sodium  cyanide 
there  will  likewise  be  modifications  in  the  blood  flow  and  respiration. 
Kholer  compressed  the  trachea  of  rabbits  by  tying  a  lead  wire 
around  it.  The  animals  recovered  from  the  operation  and  lived  four 
M'eeks.  Apparently,  to  compensate  for  the  interference  in  breathing, 
there  was  an  increased  rate  of  respiration  and  heart  activity  which 
made  good  the  oxygen  needs  of  the  organism.  In  case  of  artificial 
pneumothorax  the  hemoglobin  of  the  blood  has  been  shown  to  in- 
crease, the  pulse  rate  to  accelerate,  and  the  respiration  to  deepen. 
We  shall  discuss  later  the  adaptive  changes  which  fit  the  human 
mechanism  for  high  altitudes.  These  adaptive  reactions  are  also 
seen  in  the  blood,  in  the  breathing,  and  in  the  circulation. 

While  all  of  the  tissues  of  the  body  are  sensitive,  the  nervous  tis- 
sues are  the  most  sensitive  to  oxygen  want.  The  adaptive  responses 
to  a  lack  of  oxygen  are  undoubtedly  initiated  in  the  central  nervous 
system.  Gaser  and  Loevenhart  find  that  all  of  the  medullary  cen- 
ters in  the  brain  rerspond  in  the  same  way;  first,  by  stimulation,  and 
then  by  depression. 

The  more  definite  adaptive  altitude  changes  disclosed  by  experi- 
ments are:  (1)  An  increase  in  the  percentage  and  the  total  amount  of 
hemoglobin  in  the  blood  of  the  body  and  also  associated  w^ith  this  a 
redistribution  of  the  red  corx^uscles  whereby  a  reserve  supply  is 
thrown  into  the  general  circulation;  (2)  a  fall  in  the  lung  alveolar 
carbon  dioxide  pressure  and  a  rise  in  the  alveolar  oxygen  pressure, 
the  result  of  increased  ventilation  of  the  lungs  due  to  deeper  breath- 
ing; (3)  a  rise  in  the  arterial  blood  oxygen  pressure  which  provides 
a  partial  pressure  of  oxygen  in  the  blood  much  above  the  alveolar 
oxj'gen  pressure  in  the  lungs;  (4)  an  increase  in  the  rate  of  blood 
flow.  Each  of  these  adaptive  changes  clearly  assures  a  more  adequate 
supply  of  oxygen  for  the  tissues.  The  blood  changes  provide  for 
more  oxygen  in  a  given  unit  volume  of  blood.  The  greater  ventila- 
tion of  the  lungs  permits  a  more  thorough  saturation  of  the  hemo- 
globin with  oxygen  than  would  be  possible  if  the  oxygen  pressure  in 
the  lungs  decreased  proportionately  with  the  fall  in  barometric  pres- 
sure. The  rise  in  arterial  blood  oxygen  pressure  also  means  a  greater 
saturation  of  the  hemoglobin.  The  more  rapid  rate  of  blood  flow 
raises  to  a  limited  extent  the  oxygen  pressure  in  the  blood  passing 
through  the  tissues.    A  discussion  of  these  adaptive  changes  follows; 


AIE   SERVICE   MEDICAL.  143 

THE  CHANGES   IN   THE  BLOOD  OF  MAN   AT  HIGH  ALTITUDE. 

It  has  long  been  known  that  the  effect  of  li^p  at  high  altitudes  is 
to  cause  an  increase  in  the  number  of  red  corpuscles  per  cubic  milli- 
meter of  blood  and  an  increase  in  the  hemoglobin  percentage  of  tho 
blood.  In  1878  Paul  Bert  predicted  that  the  blood  of  man  and  ani- 
mals living  at  high  altitudes  would  be  found  to  have  a  greater 
oxygen  capacity  than  that  of  corresponding  individuals  living  at 
lower  levels.  He  surmised  that  the  cause  of  this  increase  in  the 
oxygen  carrying  power  of  the  blood  would  be  found  to  be  the  de- 
crease in  the  partial  pressure  of  the  oxygen  in  the  atmosphere  re- 
spired. In  1882  he  gave  an  account  of  some  experiments  in  which 
the  blood  obtained  from  animals  living  at  a  high  altitude  in  Bolivia 
was  found  to  contain  a  larger  percentage  of  oxygen  than  did  blood 
taken  from  animals  at  sea  level.  A  little  later,  in  1890,  Viault  ob- 
served the  increase  in  the  number  of  red  corpuscles  per  cubic  milli- 
meter of  blood  in  himself  and  his  companions  during  a  three  weeks' 
visit  in  Peru  at  an  altitude  of  14,400  feet.  Numerous  subsequent 
observations  which  have  dealt  with  these  phenomena  have  con- 
firmed beyond  question  the  earlier  data.  The  following  figures 
illustrate  the  differences  observed  in  )nankind  living  at  different 
altitudes : 

(1)  The  red  corpuscles  vary  at  sea  level  between  4.5  and  5.4 
millions  per  cubic  millimeter;  at  Colorado  Springs,  altitude  6,000 
feet,  between  5.5  and  6.3  millions;  and  on  Pike's  Peak,  altitude 
14,110  feet,  between  6  and  8.2  millions. 

(2)  The  percentage  of  hemoglobin  at  sea  level  varies  between  94 
and  106,  average  100;  in  Colorado  Springs,  105  to  118,  average  110: 
and  on  Pike's  Peak,  120  to  154,  average  144. 

(3)  The  percentage  of  oxygen  capacity  in  the  blood  at  sea  level 
varies  between  17  and  18.7;  in  Colorado  Springs,  20  and  21.7;  and 
on  Pike's  Peak,  approximately  27.4. 

Miss  Fitzgerald  has  found  that  for  every  100  mm.  fall  in  atmos- 
pheric pressure  there  is  an  average  rise  of  about  10  per  cent  in 
hemoglobin  and  that  this  rise  is  approximately  the  same  for 
women  and  men.  There  are  greater  individual  variations  in  the 
total  increase.  It  is  possible  that  under  a  pressure  greater  than 
atmospheric  the  hemoglobin  would  fall  below  100  per  cent.  The 
observations  of  Madame  Bornstein  on  animals  have  apparently  shown 
a  decrease  in  the  percentage  of  hemoglobin  when  they  were  exposed 
to  a  pressure  greater  than  atmospheric. 

Incidentally  it  is  interesting  to  note  that  the  blood  of  the  people 
living  at  high  altitudes  fails  to  show  an  increase  in  leucocytes,  but 
does  show  an  increase  in  the  lymphocyte  index.  Thus  at  sea  level 
this  index  averages  37;  at  Colorado  Springs  (6,000  feet)  42.5;  and 

8911&— 19 10 


144 


AIE  SERVICE   MEDICAL. 


on  Pike's  Peak  (14,110  feet)  50.  An  increase  in  the  number  of 
blood  platelets  as  well  as  in  the  specific  gravity  of  the  blood  has 
been  observed.  The*  following  illustrates  the  increase  in  specific 
gravity:  At  Colorado  Springs,  1.067;  after  six  months  residence  on 
Pike's*^Peak,  1.073. 

THE  SEQUENCE  IN  THE  BLOOD  CHANGES  DUKING  A  PERIOD  OF  ilESIDENCE  AT 

HIGH  ALTITUDE. 

The  facts  so  far  given  are  those  obtained  from  the  study  of  people 
who  are  acclimatized  to  the  altitude  in  which  they  are  living.  On 
passing  from  a  low  to  a  high  altitude  some  time  is  required  to  react 
to  the  low  oxygen  of  the  new  altitude.  On  ascending  passively  to 
such  an  altitude  as  14,000  feet  it  has  been  found  that  immediatelv 
after  arriving  no  change  can  be  detected  m  the  number  of  red 
corpuscles  and  the  percentage  of  hemoglobir .  Just  when  the  changes 
begin  has  not  been  determined,  but  usually  within  24  hours  a  marked 
increase  in  both  will  be  present.  A  rapid  increase  in  the  number  of 
red  corpuscles  and  percentage  of  hemoglobin  occurs  during  the  first 
two  or  four  days  of  residence ;  then  follows  a  more  gradual  increase 
extending  over  three  to  five  or  more  weeks.  These  changes  are 
illustrated  in  the  following  table : 


Date. 


Averaeo,  Colorado  Springs 

.Tune  17,  Pike's  Peak . . 

June  18.  Pike's  Pe.ik 

Tune  19,  Pike's  Peak 

Jiine  20,  Pike's  Peak 

June  21,  Pike's  Peak 

.Tune  22,  Pike's  Peak 

June  24,  Pike's  Peak 

June  26,  Pike's  Peak 

.Tune  2S,  Pike's  Peak 

June  29,  Pike's  Peak 


Havens. 

Schneider. 

Sisco. 

Hemo- 
globin. 

Corpuscles. 

Hemo- 
globin. 

Corpuscles. 

Hemo- 
globin. 

Corpuscles. 

109 

6,024,000 

109 

.-,992,000 

113 

6,372,000 

12.-5 

6,872,000 

116 

6,472,000 

120 

6,732,000 

126 

7,024,000 

115 

6,400,000 

125 

6,880,000 

129 

7,160,000 

122 

6,800,000 

126 

6,720,000 

130 

7,292,000 

121 

6,848,000 

122 

6,624,000 

i:^2 

7. 20n,  000 

12:^ 

6,73C,0W) 

130 

6,928,000 

135 

7, 296, 000 

121 

6, 472, 000 

133 

7,032,0iX) 

135 

7. 24S,  000 

126 

6,616,000 

134 

7,104,000 

134 

7. 000, 000 

127 

6,656,000 

131 

ft,  856, 000 

129 

6,840,000 

129 

6, 896, 000 

135 

■    7,120,000 

132 

6,976,000 

129 

6, 960  000 

Views  differ  as  to  the  mechanism  by  which  the  changes  in  hemo- 
globin and  red  corpuscles  are  brought  about.  These  views  may  be 
conveniently  divided  into  three  main  classes:  (1)  Those  theories 
which  insist  that  the  increase  in  hemoglobin  and  red  corpuscles  is 
real  and  not  merely  relative;  two  explanations  of  the  increase  have 
been  proposed:  (a)  that  the  increase  is  due  to  increased  activity  of 
the  blood-forming  organs,  resulting  in  an  increase  in  the  hemoglobin 
and  red  corpuscles;  (h)  that  the  increase  is  due  to  a  lengthening,  of 
the  life  of  the  corpuscles.  (2)  The  concentration  theories,  according 
to  which  the  increase  in  hemoglobin  and  red  corpuscles  per  unit 
volume  is  due  to  increased  concentration  of  the  blood.     According 


AIE  SERVICE   MEDICAL.  145 

to  this  view,  the  increase  in  both  is  only  apparent,  and  there  is  no 
increase  in  the  total  number  of  red  corpuscles  and  the  amount  of 
hemoglobin  in  the  body.  (3)  It  has  been  held  that  the  increase  in 
hemoglobin  and  corpuscles  is  clue  to  unequal  distribution  of  the  red 
corpuscles.  They  are  supposed  to  be  more  numerous  in  the  blood  of 
the  capillaries  and  smaller  vessels  and  less  numerous  in  the  Targe 
vessels.  This  view  has  not  been  supportecl  experimentally  and  may 
be  considered  untenable.  It  has  further  been  supposed  that  there 
exists  in  the  body  a  reserve  or  dormant  supply  of  red  corpuscles 
which  is  drawn  upon  at  high  altitudes.  The  discussion  at  issue  seems 
to  permit  the  following,  conclusion:  The  initial  rapid  increase  in 
hemoglobin  and  red  corpuscles  is  brought  about  in  part  by  the  pass- 
ing into  the  systemic  circulation  of  a  large  number  of  red  corpuscles 
that  under  ordinary  circumstances  at  low  altitudes  are  sidetracked 
and  inactive,  and  in  part  by  a  concentration  resulting  from  a  loss  of 
fluid  from  the  blood.  The  more  gradual  increase  in  red  corpuscles 
and  hemoglobin  extending  over  several  weeks  is  brought  about  by  an 
increased  activity  of  the  blood-forming  centers,  so  that  there  results 
an  actual  increase  in  the  total  number  of  corpuscles  and  the  amount 
of  hemoglobin.  The  evidence  for  the  above  statement  can  be  briefly 
sum.marized.  Schneider  and  Havens  have  shown  that  abdominal 
massage  and  physical  exertion  at  low  altitudes  cause  an  increase  in 
the  number  of  red  corpuscles  and  hemoglobin  in  the  peripheral  capil- 
laries ;  wliile  in  men  partially  or  wholly  acclimatized  to  a  high  alti- 
tude abdominal  massage  either  does  not  change  or  lowers  the  content 
of  hemoglobin  and  red  corpuscles,  and  physical  exertion  fails  to 
cause  an  increase.  This  failure  to  obtain  an  increase  at  high  altitude 
may  be  accounted  for  on  the  assumption  that  the  need  for  oxygen 
has  called  into  permanent  circulation  the  reserve  supply  of  cor- 
puscles that  is  present  at  low  altitude.  That  an  actual  concentration 
of  the  blood  occurfe  during  the  first  few  days  of  residence  at  high 
altitude  was  proven  for  three  subjects  by  Douglas,  Haldane,  Hender- 
son, and  Schneider  during  an  investigation  made  on  Pike's  Peak. 
One  of  their  subjects  had,  after  a  few  days  of  residence,  about  a 
15  per  cent  increase  in  hemoglobin  and  a  total  blood  volume  10.8  per 
cent  less  than  at  Colorado  Springs  (altitude  6,000  feet).  Dreyer  and 
Walker,  reviewing  Abderhalden's  data,  found  that  a  little  less  than 
half  of  a  25  per  cent  increase  of  the  hemoglobin  in  rabbits,  that  Ab- 
derhalden  concluded  was  due  to  concentration,  was  actually  a  result 
of  concentration,  while  the  balance  of  it  was  to  be  explained  by  a  new 
formation  of  hemoglobin.  That  there  is  also  an  active  new  formation 
of  hemoglobin  and  red  corpuscles  is  indicated  by  several  researches. 
Thus,  Zuntz  and  co-workers  found,  on  comparing  stained  sections  of 
bone  marrow  taken  from  dogs,  one  group  of  which  had  been  kept 
at  sea  level  and  the  second  at  a  high  altitude,  that  the  latter  show 


146  AIE  SERVICE   MEDICAL. 

a  decrease  in  fat  cells  and  an  increase  in  the  blood  elements.  This, 
they  concluded,  indicated  increased  activity  of  the  corpusclerproduc- 
ing  centers  at  the  high  altitude.  Douglas,  Haldane,  Henderson,  and 
Schneider,  by  the  carbon-monoxide  method  of  Haldane  and  Lorraine 
Smith,  found  that  during  a  residence  of  five  weeks  on  Pike's  Peak 
(altitude  14,110  feet)  four  men  had  a  large  increase  in  the  total 
amount  of  hemoglobin  and  also  an  increase  in  the  total  volume  of 
blood.  Laquer  found  that  dogs  deprived  of  hemoglobin  of  half  of 
their  blood  supply  regenerated  it  in  about  16  days  on  Monte  Eosa, 
while  at  a  low  altitude  27  days  were  required  for  the  restoration 
after  a  similar  hemorrhage. 

It  has  been  shown  in  studies  on  Pike's  Peak  that  the  increase  in 
hemoglobin  and  red  corpuscles  for  an  individual  is  not  the  same  dur- 
ing several  trips  and  sojourns  at  that  altitude.  The  increase  occurs 
most  rapidly  when  the  subject  is  in  excellent  physical  condition.  If 
prior  to  the  ascent  his  life  has  been  sedentary  and  he  is  known  to  be 
physically  unfit  the  changes  will  be  slow  in  beginning,  and  the  in- 
crease when  followed  day  by  day  will  be  moderate  or  slight.  If,  on 
the  other  hand,  the  subject  has  taken  regular  physical  exercise  and 
is  in  excellent  condition  or  physically  fit  there  will  be  a  decided  rise 
in  both  hemoglobin  and  red  corpuscles  in  the  first  24  hours  spent  at 
the  high  altitude.  It  has  also  been  shown  that  fatigue,  induced  by 
walking  up  a  mountain,  delays  the  increase  in  hemoglobin  and  red 
corpuscles.  The  lesson  to  be  gained  from  these  observations  is  that 
physical  fitness  qualifies  the  subject  to  react  quickly  when  under  the 
influence  of  the  low  oxygen  at  high  altitudes. 

CIRCULATION    AT    HIGH    ALTITUDES. 

There  has  been  a  great  interest  in  the  problem  of  circulation  at 
high  altitudes.  Many  persons,  especially  those  with  weak  hearts, 
have  an  unwarranted  fear  of  high  altitudes  because  they  have  been 
informed  that  they  injure  the  heart.  The  early  studies  have  been 
of  a  fragmentary  nature,  the  observations  being  confined  wholly  to  a 
study  of  pulse  rate  and  the  systolic  blood  pressure.  It  has  recently 
been  shown  that  there  is  an  increased  rate  of  blood  flow  at  very  high 
altitudes.  This  is  a  compensatory  reaction  which  will  insure  to  the 
tissues  a  more  adequate  blood  supply.  A  more  rapid  rate  of  blood 
flow  will  raise  to  a  limited  extent  the  oxygen  pressure  in  the  blood 
passing  through  the  capillaries,  and  so  insure  better  oxidation  within 
the  tissues.  The  recent  investigations  have  included  observations 
on  the  pulse  rate,  arterial  pressures,  capillary  pressure,  and  venous 
blood  pressure.  Indirect  methods  have  also  been  employed  with  the 
hope  of  determining  the  output  of  the  heart  per  beat  as  well  as  the 
rate  of  blood  flow  through  the  lungs  and  other  tissues. 


AIB  SJtRVICE   MEDICiJ*  147 

THE   PULSE   RATE. 

Of  all  the  circulatory  changes  due  to  diminished  barometric  pres- 
sure the  acceleration  of  the  heart  rate  is  the  most  noticeable.  The 
majority  of  the  earlier  records  are  from  studies  made  of  men  who 
had  undergone  considerable  physical  exertion  in  climbing  a  moun- 
tain. The  fatigue  thus  induced  has  obscured  the  early  influence  of 
altitude.  Therefore,  in  order  to  understand, the  reaction  of  the  heart 
it  is  necessary  to  eliminate  all  extraneous  modifying  influences  such 
as  fatigue  and  cold.  Pike's  Peak  offers  an  excellent  opportunity  for 
such  Alpine  physiological  studies,  because  men  may  be  carried  up 
passively  by  railway  or  in  an  automobile. 

It  is  generally  recognized  that  at  moderately  high  altitudes,  6,000 
to  8,000  feet,  or  even  9,000  feet,  the  inhabitants  do  not  show  an  aug- 
mentation in  heart  rate.  There  is  considerable  variation  in  pulse 
rate  of  different  healthy  individuals  at  sea  level.  Thus  it  was  found 
that  athletes  in  Oxford  had  rates  which  may  be  considered  normal 
that  range  between  44  and  80..  In  a  study  of  medical  students  at 
Cambridge  the  range  was  between  47  and  90,  The  same  limits  will 
be  found  in  men  acclimated  to  the  moderate  altitudes. 

On  ascending  passively  to  a  high  altitude,  such  as  14,000  feet,  there 
is  at  first  no  noticeable  increase  in  the  rate  of  heart  beat.  What  hap- 
pens after  the  ascent  depends  on  the  condition  of  the  subject.  If  he 
has  ascended  much  beyond  what  has  been  spoken  of  as  the  critical 
altitude  line  for  the  individual  an  attack  of  mountain  sickness  is  to 
be  expected.  If  he  has  not  passed  his  critical  line,  or  only  reached  it, 
his  pulse  rate  will  continue  for  some  hours  at  the  tempo  common 
to  it  at  the  lower  altitude.  Any  exertion  will  obscure  the  altitude 
reaction;  if,  however,  he  remains  quiet,  by  the  next  morning,  even 
while  still  in  bed,  the  pulse  rate  will  be  slightly  accelerated.  Each 
successive  morning  for  three  to  five  days  the  rate  will  be  found  to  be 
somewhat  greater  than  on  the  previous  morning.  The  following 
example  illustrates  the  amoimt  of  change :  Thus  one  subject  who  had 
in  Colorado  Springs  (altitude  6,000  feet)  an  average  early  morning 
rate  of  53,  had  on  Pike's  Peak  the  first  morning  a  rate  of  58;  the 
second  60 ;  the  third  63 ;  and  the  fourth  66.  In  those  who  are  influ- 
enced by  altitude  sickness  the  story  is  different.  The  heart  accel- 
erates as  the  attack  of  mountain  sickness  comes  on,  and  the  early 
morning  pulse  rate  may  have  reached  its  maximum  by  the  first 
morning.  As  the  attack  passes  off  the  heart  will  slow.  An  example 
of  this  reaction  is  found  in  the  following  subject,  who  had  in  Col- 
orado Springs  an  average  early  morning  pulse  rate  of  61,  He  became 
mountain  sick  six  hours  after  arriving  at  the  summit  of  Pike's  Peak. 
His  pulse  rate  the  next  morning  was  89,  slowing  to  80  the  second;  to 
S9118— 19 11 


148  AIE   SERVICE   MEDICAL. 

78  the  third ;  and  to  72  on  the  fifth  morning.  In  men  who  undergo 
the  exertion  of  climbing  a  mountain  the  pulse  rate  reaction  is  quite 
like  that  observed  in  those  who  become  mountain  sick.  The  increase 
in  the  heart  rate  has  been  found  to  range  from  30  to  74  per  cent. 
The  amount  of  acceleration  at  high  altitudes  is  determined  to  some 
extent  by  physical  fitness.  There  will  be  less  acceleration  in  the  man 
who  is  in  the  pink  of  condition,  while  the  augmentation  is  great  in 
those  who  had  been  leading  a  sedentary  life  and  are  physically  below 
par.  The  daily  mean  pulse  rate  for  men  at  high  altitudes  shows 
approximately  the  same  proportionate  increase  as  the  early  morning 
pulse  rate  does  when  compared  with  rates  experienced  at  lower  alti- 
tudes. The  influence  of  posture  upon  pulse  rate  has  been  investi- 
gated, and  it  has  been  established  that  the  heart  is  not  necessarily 
more  irritable  to  changes  in  body  position  at  high  than  at  low  alti- 
tudes. In  general  it  may  be  said  that  the  heart  works  at  an  increased 
rate  in  all  postures  at  the  high  altitude.  The  amount  of  increase  in 
the  pulse  rate  differs  with  individuals.  Some  men  will  show  at  the 
high  altitude,  such  as  14,000  feet,  an  acceleration  of  only  a  few  beats 
over  the  low  altitude  rate,  while  others  show  an  increase  of  10  or 
more  beats  per  minute. 

During  a  sojourn  at  a  high  altitude  the  pulse  rate  may  show  a 
gradual  daily  increase  for  a  period  of  one  or  two  weeks,  ordinarily 
not  more  than  one  week.  With  longer  residence  there  is  a  tendency 
to  return  toward  the  low  altitude  rate.  It  appears  that  the  slowing 
of  the  heart  takes  place  as  other  adaptive  changes  reach  their  maxi- 
mum efficiency.  Rarely  does  the  pulse  rate  return  completely  to  the 
normal  rate  of  the  low  altitude. 

ARTERIAL   PRESSURES. 

In  recent  years  stress  has  been  laid  on  blood  pressure  findings  at 
high  altitudes,  the  value  of  which  has  undoubtedly  been  overesti- 
mated. Just  what  normal  blood  pressures  are  at  sea  level  is  a  matter 
concerning  which  there  is  the  widest  diversity  of  opinion.  Janeway 
states  that  "  in  the  great  majority  of  young  males,  100  to  130  mm. 
will  be  found  ",  and  names  the  normal  diastolic  pressure  as  from  65 
to  110.  Faught  states  that  120  may  be  taken  as  the  normal  systolic 
pressure  in  the  male  at  the  age  of  20  and  adds  1  millimeter  for  every 
additional  2  years  of  life.  He  believes  that  the  question  as  to  what 
variations  from  this  are  normal  can  not  be  definitely  answered,  but 
suggests  17  mm.  above  or  below,  or  a  total  variation  of  34.  The 
most  satisfactory  data  on  blood  pressures,  as  far  as  the  interpreta- 
tion of  altitude  effect  is  concerned,  is  that  obtained  from  observations 
made  upon  the  same  men  at  both  a  low  and  a  high  altitude.  Such 
comparisons  have  been  made  on  Pike's  Peak.     Data,  accumulated 


AIB   SERVICE   MEDICAL.  149 

during  a  period  of  more  tlian  5  years  in  the  laboratory  at  Colorado 
College  in  Colorado  Springs,  show  that  at  an  altitude  of  6,000  feet 
the  systolic  pressure  is  in  the  majority  of  young  men  less  than 
120  mm.  and  falls  within  the  range  given  by  Janeway.  The  dias- 
tolic pressure  likewise  corresponds  to  that  observed  in  young  men 
at  sea  level.  We  may  conclude  then  that  at  moderate  altitude,  nor- 
mal healthy  young  men  show  the  same  range  and  distribution  of 
pressures  as  do  young  men  at  sea  level. 

INIany  physicians  still  believe  that  at  high  altitudes,  such  as  14,000 
feet,  the  blood  pressure  increases  simultaneously  with  the  decrease 
in  atmospheric  pressure,  and  they  conclude  that  this  increase  means 
injury,  especially  to  the  weakened  heart.  The  investigations  of 
more  recent  years  show  that  this  opinion  is  untenable.  The  observa- 
tions on  Pike's  Peak  which  extend  over  a  number  of  years  and  which 
were  made  upon  men  who  ascended  the  mountain  passively  show 
that  in  those  who  react  well  to  the  altitude  the  changes  were  sur- 
prisingly slight,  in  fact,  they  were  so  slight  that  they  fall  for  the 
most  part  within  the  errors  of  observations.  Schneider  and  Sisco 
concluded  that  for  manj',  and  very  likely  the  vast  majority  of  healthy 
men,  an  altitude  of  14.000  feet  does  not  influence  the  arterial  blood 
pressures.  In  a  certain  but  as  yet  undetermined  percentage  of  men 
this  altitude  will  cause  a  demonstrable  fall,  and  in  exceptional  men, 
particularly  those  who  do  not  react  well  to  the  high  altitude,  will 
bring  about  a  rise  in  the  arterial  pressures. 

During  an  attack  of  mountain  sickness  there  will  be  manifested  a 
disturbance  in  circulation,  as  shown  by  the  definite  rise  in  the  arterial 
pressures.  Thus  in  one  subject  the  following  changes  in  pressure 
were  noted  during  and  after  an  attack  of  mountain  sickness:  In 
Colorado  Springs,  6,000  feet,  he  averaged  in  systolic  pressure  118. 
and  in  diastolic  85.  On  going  to  the  summit  of  Pike's  Peak  he  was 
ill  with  mountain  sickness  the  first  three  days,  during  which  time 
his  systolic  pressure  averaged  129,  and  the  diastolic  pressure  91. 
However,  by  the  morning  of  the  fourth  day  he  was  decidedly  better, 
in  fact,  had  recovered,  and  during  the  next  three  days  his  systolic 
pressure  averaged  116,  and  the  diastolic  84.  The  fear  of  high  alti- 
tudes undoubtedly  is  a  result  of  over-emphasis  of  the  circulatory  con- 
ditions observed  during  the  early  days  spent  at  a  high  altitude  when 
the  organism  has  not  as  yet  accommodated  itself  to  the  new  condi- 
tions of  environment.  Certainly  after  adjustment  the  blood  pres- 
sures do  not  show  an  important  change. 

VENOUS  BLOOD  PRESSTJKE. 

Venous  pressures  have  not  received  the  same  amount  of  attention 
at  either  high  or  low  altitudes  as  have  the  arterial  pressures.  It  is 
only  in  recent  years  that  satisfactory  methods  of  observing  venous 


150  AIR   SERVICE   MEDICAL. 

pressure  have  been  available.  Hooker  in  Baltimore  finds  that  in 
healthy  men  the  venous  pressure  varies  or  ranges  between  2  and 
16  centimeters  of  water.  Schneider  and  Sisco  found  the  same  pres- 
sures may  be  considered  as  normal  on  healthy  young  men  at  an  alti- 
tude of  6,000  feet.  On  Pike's  Peak  they  find  a  marked  fall  of  betweer. 
20  and  87  per  cent  in  the  venous  pressure  of  healthy  young  men. 
The  changes  in  venous  pressure  occurred  slowly,  in  fact,  in  some  of 
their  subjects  the  pressure  was  somewhat  higher  during  the  first  half 
day  spent  at  the  higher  altitude.  While  the  venous  pressure  was 
shown  to  fall,  they  found  the  venous  supply  of  blood  and  the  venous 
pressure  remained  sufficient  at  the  altitude  to  give  a  maximum  effi- 
ciency of  heartbeat. 

CAPILLARY  BLOOD  PRESSURE. 

Lombard  has  shown  for  low  altitudes  that  the  most  compressible 
capillaries  disappear  at  a  jjressure  between  15  and  25  millimeters 
of  mercury.  The  aA^erage  capillary  between  35  and  45  millimeters, 
and  the  most  resisting  capillaries  between  60  and  70  millimeters. 
On  Pike's  Peak  the  capillary  pressures  were  in  some  men  slightly 
lower  than  when  at  an  altitude  of  6,000  feet,  while  in  others  the 
capillary  pressures  were  unaffected  by  altitude. 

It  has  been  frequently  claimed  that  bleeding  from  the  nose,  lips, 
gums,  lungs,  and  stomach  is  a  common  experience  at  high  altitudes 
and  this  has  been  attributed  to  increased  capillary  pressure.  The 
above  observations  show  this  conclusion  to  be  incorrect.  Among  the 
thousands  of  people  that  ascend  Pike's  Peak  every  summer  there  oc- 
cur only  a  few  cases  of  hemorrhage  and  these  are  of  the  nose  only. 
Such  cases  are  so  rare  that  doubt  would  be  thrown  on  the  usual  ex- 
planation, even  in  the  absence  of  positive  proof  that  capillary  pres- 
sure is  not  increased  with  altitude. 

THE  OUTPUT  OF  THE  HEART  AND  THE  RATE  OF  BLOOD  FLOW. 

Attempts  made  to  determine  the  output  of  blood  per  beat  from  the 
heart  have  not  been  very  successful.  By  use  of  the  recoil  method 
of  Yandell  Henderson  the  mass  movement  of  the  blood  has  been 
studied  on  Pike's  Peak.  The  observations  indicate  that  the  output 
of  the  heart  is  either  the  same  as  at  low  altitude  or  may  be  slightly 
less.  It  is  assumed  that  the  pulse  pressure  is  an  index  of  the  heart 
output  per  beat.  Since  it  has  been  shown  that  the  pulse  pressure  is 
the  same  at  the  high  and  low  altitudes  for  particular  subjects  under 
observation  we  may  be  permitted  to  conclude  that  the  output  of  the 
heart  is  unchanged  with  altitude.  If  the  pulse  rate  be  multiplied  by 
the  pulse  pressure  and  the  product  be  taken  as  a  relative  measure  of 
the  volume  of  the  blood  stream  per  minute,  a  marked  increase  in  the 
circulation  rate  is  indicated  for  high  altitudes. 


AIE   SERVICE   MEDICAL.  151 

That  the  rate  of  blood  flow  is  increased  with  altitude  has  been 
shown  by  two  researches.  Schneider  and  Sisco  used  Stewart's  calo- 
rimeters to  determine  the  rate  of  the  blood  flow  through  the  hands. 
The  method  determines  the  amount  of  heat  given  off  by  the  resting 
hand  in  a  given  time  and  indirectl}'  the  temperatures  of  the  arterial 
and  venous  blood.  With  these  data  it  is  possible  to  calculate  how 
much  blood  has  passed  through  the  hand  in  order  that  it  might  give 
off  a  determined  amount  of  heat.  By  tins  method  the  blood  flow 
through  100  c.  c.  of  hand  volume  was  shown  to  be  from  30  to  70  per 
cent  greater,  in  six  men  studied,  on  the  summit  of  Pike's  Peak  than 
in  Colorado  Spi'ings.  Kuhn,  on  Monte  Rosa,  also  has  demonstrated, 
by  calculations  made  from  determinations  of  the  oxygen  capacity  of 
the  blood,  the  total  oxygen  consumption  and  the  pulse  rate,  that  the 
per  minute  output  of  the  heart  is  increased  at  that  high  altitude. 

WHAT  CAUSES  THE  CIRCUIiATORY  CHAKGE8  REPORTED  AND  THE  INCREASED 

RATE    IN    FT.OW? 

All  adaptive  changes  occurring  at  high  altitudes  seem  to  be  for  the 
purpose  of  supplying  a  more  adequate  supply  of  oxygen  for  the 
tissues.  If,  therefore,  oxygen  want  is  the  cause  of  the  observed  in- 
crease in  the  flow  of  the  blood,  it  is  to  be  expected  that  the  inhalation 
of  pure  oxygen  while  at  the  high  altitude  may  so  benefit  the  body 
as  to  retard  the  heart  and  diminish  the  rate  of  the  blood  flow. 
Schneider  and  Sisco  found  that  the  breathing  of  an  oxygen-rich  mix- 
ture while  on  Pike's  Peak  slowed  the  heart  appreciably  and  dimin- 
ished the  rate  of  the  blood  flow  through  the  hands;  from  which  we 
may  conclude  that  lack  of  oxygen  calls  forth  certain  definite  circu- 
latory responses  in  men  for  the  purpose  of  increasing  the  rate  of 
blood  flow,  in  order  that  the  oxygen  pressure  may  be  sufficient  to  fur- 
nish the  tissues  with  the  oxygen  needed  as  the  blood  passes  through 
the  capillaries. 

THE    EFFECTS    OF    PHYSICAL    EXERTION    ON    THE    PULSE    RATE    AND    THE 
BLOOD  PRESSURES  AT  HIGH  ALTITUDE. 

The  normal  circulatory  conditions  for  the  majority  of  men  at 
high  altitudes  are  an  increased  rate  of  heart  beat  and  an  unchanged, 
or  slightly  lowered,  arterial  pressure,  and  a  lowered  venous  pres- 
sure. All  investigators  haVe  found  that  a  more  marked  increase  in 
the  pulse  rate  occurs  during  work  at  a  high  than  results  with  the 
same  exertion  at  a  low  altitude.  Just  what  height  must  be  reached 
before  altitude  accelerates  the  exercise  pulse  rate  has  not  been  defi- 
nitely determined,  but  the  inhabitants  at  6,000  feet  show  no  notice- 
able exercise  altitude  effect.  Observations  on  the  after-effects  of 
walking  for  15  minutes  at  the  rate  of  3  and  4  miles  per  hour,  show 


152  AIR  SERVICE  MEDICAL. 

clearly  that  physical  exertion  accelerates  the  heart  more  at  a  high 
than  at  a  low  altitude  and  that  the  influence  is  disproportionately 
increased  as  the  amount  of  work  is  increased.  The  effect  of  the 
lowered  barometric  pressure  is  manifest  not  only  in  the  greater  ac- 
celeration of  the  heart,  but  in  the  great  extention  in  the  time  required 
for  the  rate  to  return  to  the  normal  after  work  has  ceased.  Further- 
more, these  altitude  reactions  are  greatest  during  the  first  days  and 
become  less  as  the  individual  becomes  acclimated.  The  arterial  pres- 
sures will  be  higher  after  a  given  rate  of  walking  at  a  high  altitude 
than  after  the  same  amount  of  work  at  a  lower  altitude.  Here  like- 
wise the  greater  the  exertion  the  more  pronounced  is  the  influence  of 
lowered  barometric  pressure.  In  physicall}^  fit  men  the  effect  of  al- 
titude is  much  less.  The  facts  show  that  the  heart  and  the  blood 
vessels  undergo  a  greater  strain  under  exertion  at  the  high  than 
is  experienced  for  the  same  form  of  exercise  at  low  altitudes.  The 
excessive  response  of  the  circulatory  mechanism  during  and  immedi- 
ately following  physical  work  is  greatest  during  the  first  days ;  and 
descreases,  particularly  for  moderate  exertion,  as  the  bodily  changes 
of  the  acclimatization  progress.  For  persons  in  excellent  physical 
condition  and  who  have  reacted  well  to  the  altitude  the  changes  of  the 
acclimatization  will  permit  of  moderate  exertion  without  a  lowered 
barometric  pressure  manifesting  itself  by  the  more  pronounced  ac- 
celeration of  heart  rate  and  increased  blood  pressure.  The  evidence 
at  hand  makes  it  probable  that  in  vigorous  work,  even  in  those  who 
are  best  adapted  to  the  high  altitudes,  one  will  continue  to  get  a 
more  pronounced  reaction  than  would  occur  at  a  low  altitude.  In 
order  that  the  effects  of  acclimatization  may  be  better  understood 
the  following  examples  of  the  circulatory  effects  of  altitude  are 
given:  Walking  for  15  minutes  at  the  rate  of  3  miles  an  hour  in 
Colorado  Springs  one  subject  had  the  following  changes:  An  in- 
crease of  11  beats  in  pulse  rate  and  no  change  in  systolic  and  diastolic 
pressures.  During  the  first  day  spent  on  Pike's  Peak  a  similar  walk 
accelerated  the  pulse  34  beats,  caused  a  rise  in  the  sj'stolic  pressure 
of  28  mm.,  and  in  the  diastolic  4  mm.  On  the  fourth  day  of  resi- 
dence this  amount  of  work  accelerated  the  pulse  only  24  beats,  in- 
creased the  systolic  pressure  8  mm.,  and  did  not  affect  the  diastolic 
pressure.  This  same  subject,  walking  at  the  rate  of  4  miles  per  hour 
for  15  minutes  in  Colorado  Springs  had  the  following  reactions: 
Average  increase  in  pulse,  24  beats;  systolic  pressure,  6  mm.;  and 
diastolic  pressure,  1  mm.  The  first  day  spent  on  Pike's  Peak,  this 
amount  of  exercise  accelerated  to  pulse  61  beats,  systolic  pressure 
44  mm.,  and  diastolic  pressure  7  mm.  On  the  fourth  day  the  pulse 
increased  54  beats,  systolic  23  mm.,  and  diastolic  4  mm.  These 
observations  suggest  that  it  would  be  best  to  avoid  physical  work 
during  the  first  days  spent  at  very  high  altitudes. 


ATE  SERVICE  MEDICA-L.  153 

It  is  to  be  expected  that  living  at  a  high  altitude,  especially  when 
much  physical  work  is  done,  will  increase  the  weight  of  the  heart, 
for  all  muscular  exertion  tends  to  increase  the  weight  of  the  heart, 
and  the  result  of  the  work  at  high  altitudes  would  accentuate  the 
tendency.  Strohl  compared  the  heart  of  Alpine  snow  birds  living  at 
altitudes  ranging  from  6,700  to  10,000  with  the  Moor  snow  bird, 
which  is  not  found  above  2,000  feet,  and  found  that  the  average 
weight  of  the  heart  of  the  Alpine  snow  bifd  was  about  46  per  cent 
heavier  than  that  of  the  Moor  bird.  The  hypertrophy  of  the  right 
was  greater  than  that  of  the  left  ventricle.  He  made  one  observation 
of  considerable  interest,  in  which  he  found  that  the  heart  of  a 
young  Alpine  snow  bird  one  and  a  half  months  old  had  the  same 
proportions  in  weight  as  that  of  the  Moor  snow  bird,  which  suggests 
that  the  differences  ordinarily  observed  at  the  two  altitudes  are  due 
to  the  greater  circulatory  reactions  called  forth  during  muscular 
work  at  the  high  altitude. 

RESPIRATION    AT   HIGH    ALTITUDE. 

It  has  been  known  since  the  researches  by  Haldane  and  pupils 
that  the  volume  of  fresh  air  taken  into  the  lungs  per  minute  during 
rest  is  so  regulated  as  to  keep  the  partial  pressure  of  carbon  dioxide 
in  the  alveolar  air  practically  constant  for  the  individual.  There- 
fore the  carbon  dioxide  content  of  the  alveolar  air  is  taken  as  an 
index  of  lung  ventilation.  The  breathing,  however,  is  dependent  on 
the  integrity  of  a  very  small  area,  the  respiratory  center,  of  the  brain 
in  the  medulla  oblongata.  The  reaction  of  this  center  is  regarded  as 
automatic,  and  any  interference  with  its  supply  of  properly  aerated 
blood  causes  greatly  increased  activity  and  thereby  increased  breath- 
ing. Carbon  dioxide  in  the  blood  is  the  stimulant  which  excites  this 
nervous  center  of  our  respiratory  mechanism  and  maintains  its 
regular  action.  There  is  no  doubt  that  slight  changes  in  carbon  di- 
oxide in  the  blood  affect  the  respiratory  center.  The  effects  of  these 
changes  are  rapid  and  marked  when  in  laboratory  experiments  with 
animals  all  the  nervous  connections  between  the  lungs  and  the 
respiratory  center  are  severed.  A  decrease  in  the  amount  of  oxygen 
in  the  blood  will  also  affect  the  respiratory  center.  It  is  generally 
held  that  the  amount  of  oxygen  must  be  markedly  lowered  before  the 
respiratory  center  begins  to  be  stimulated  by  the  decrease  in  oxygen. 
For  our  present  purposes,  the  explanation  of  the  breathing  changes 
at  high  altitudes,  attention  may  be  centered  on  the  carbon  dioxide 
content  of  the  blood  and  in  the  alveoli  of  the  lungs.  Both  the  per- 
centage of  oxygen  and  that  of  carbon  dioxide  are  very  constant  in 
the  alveolar  air  in  spite  of  great  changes  in  the  amount  of  oxygen 
consumed  and  carbon  dioxide  given  off  by  the  body.  Since  the 
volume  of  fresh  air  taken  into  the  lungs  per  minute  is  so  regulated 


154  AIB  SEKVICE  MTECTCAL. 

as  to  keep  the  partial  pressure  of  carbon  dioxide  in  the  alveolar  air 
practically  constant  for  each  individual  (at  about  40  mm.  for  adult 
men  at  sea  level),  the  alveolar  ventilation  must  vary  according  to  the 
mass  of  carbon  dioxide  given  off.  Even  during  muscular  work  this 
rule  holds  approximately  true  under  ordinary  conditions.  A  diminu- 
tion in  the  alveolar  carbon  dioxide  pressure  has  been  found  to  indi- 
cate an  increase  in  the  lung  ventilation,  while  an  increase  in  carbon 
dioxide  means  lessened  ventilation  and  a  reduction  in  alveolar 
oxygen. 

The  ventilation  of  the  lungs  for  people  dwelling  at  high  altitudes 
is  greater  than  that  of  mankind  living  at  sea  level.  On  going  from 
sea  level  to  an  altitude  of  6,000  feet,  with  a  fall  of  about  145  mm. 
from  normal  in  barometric  pressure,  the  alveolar  carbon  dioxide  pres- 
sure is  lowered  about  4  mm. ;  and  on  further  ascending  to  the  summit 
of  Pike's  Peak  (14,110  feet)  with  an  added  decrease  of  about  160 
mjn.  in  barometric  pressure,  the  alveolar  carbon  dioxide  pressure 
falls  on  an  average  about  10  mm.  more.  This  is  a  little  more  than  a 
30  per  cent  decrease  and  indicates  a  corresponding  increase  in  the 
breathing.  The  full  extent  of  the  fall  takes  about  two  weeks  to  de- 
velop, and  thereafter  the  carbon  dioxide  pressure  will  remain  prac- 
tically steady. 

If  the  same  alveolar  carbon  dioxide  pressure  were  to  be  maintained 
on  Pike's  Peak  with  a  barometric  pressure  of  about  457  mm.  that  is 
normal  at  sea  level,  there  would  be  a  marked  shortage  of  oxygen.  This 
would  be  true,  because  a  deficiency  of  oxygen  in  the  alveolar  air 
always  runs  parallel  to  the  excess  in  carbon  dioxide.  If  the  carbon 
dioxide  pressure  remained  at  40  mm.  while  the  atmospheric  pressure 
had  fallen  from  760  to  457  mm.,  it  would  amount  to  a  relative  in- 
crease of  about  27  per  cent  in  the  carbon  dioxide  and  a  similar 
decrease  in  oxygen.  The  partial  pressure  of  oxygen  in  the  alveolar 
air  would  therefore  be  about  50  mm.  lower  than  in  the  inspired  air. 
Allowing  for  the  pressure  of  aqueous  vapor  at  body  temperature,  it 
is  found  that  the  pressure  of  oxygen  in  the  lungs  at  the  altitude  of 
Pike's  Peak  would  be  36  mm.  This  is  an  oxygen  pressure  which 
would  be  found  if  dry  alveolar  air  contained  only  5  per  cent  of 
oxygen  at  normal  atmospheric  pressure,  and  it  is  known  that  marked 
symptoms  of  want  of  oxygen  are  ordinarily  produced  under  such 
conditions.  Parallel  with  the  fall  of  about  13  mm.  in  the  alveolar 
carbon  dioxide  pressure  on  Pike's  Peak  there  occurs  a  rise  in  the 
alveolar  oxygen  pressure  of  a  little  more  than  16  mm.  so  that  the 
alveolar  oxygen  pressure  at  that  altitude  is  about  52  mm.  This  rise  in 
the  oxygen  above  what  might  be  expected  when  carbon  dioxide  re- 
mains unchanged  is  due  to  increased  breathing. 

On  going  to  a  verv^  high  altitude  the  breathing  is  increased  at 
once  and  the  alveolar  carbon  dioxide  pressure  falls  correspondingly, 


AIB   SERVICE  MEDICAL. 


155 


hut  if  the  altitude  is  only  very  moderate  there  is  at  first  no  effect  on 
the  breathing.  After  some  days,  however,  it  will  be  found  that  the 
alveolar  carbon  dioxide  pressure  has  fallen,  indicating  that  the  breath- 
ing is  deeper.  The  fall  reaches  a  certain  amount  and  the  breathing 
a  certain  depth,  depending  on  the  altitude,  and  then  ceases.  Studies 
on  persons  residing  permanently  at  different  altitudes  show  that 
there  is  a  progressive  decrease  in  the  alveolar  carbon  dioxide  pres- 
sure corresponding  to  increase  in  altitude.  For  every  fall  of  100 
mm.  of  barometric  pressure  there  is  approximately  a  fall  of  4.2  mm. 
in  the  pressure  in  the  alveolar  carbon  dioxide.  There  is  likewise  a 
progressive  fall  in  the  oxygen  pressure,  but  this  does  not  follow 
exactly  the  same  ratio  as  the  carbon  dioxide  changes.  The  following 
illustrates  alveolar  air  altitude  changes: 


Sea-levcl . 
6,000  feet . 
14,100  feet 
34,600  feet 


Carbon 

Barometer. 

dioxide 

pressiire. 

Mm. 

760 

40 

615 

36 

458 

27 

312 

21 

Oxygen 
pressure. 


Mm. 


100 
78 
53 
33 


That  the  diminution  in  carbon  dioxide  is  a  response  to  the  dimin- 
ished oxygen  pressure  there  can  be  no  doubt.  If  the  barometric  pres- 
sure is  kept  steady  and  the  oxygen  pressure  is  diminished  by  lower- 
ing the  percentage  of  oxygen,  the  results  are  precisely  the  same  as 
those  obtained  with  changes  in  altitude. 

Since  the  content  of  carbon  dioxide  and  oxygen  in  the  lung  alveoli 
give  an  index  of  the  total  ventilation  of  the  lungs  in  breathing,  fre- 
quent chemical  analyses  of  the  alveolar  air  during  and  after  an  ascent 
will  indicate  how  much  the  breathing  is  increasing.  As  stated  above, 
the  breathing  responds  at  once  as  an  ascent  is  made,  but  the  changes 
are  not  completed  for  several  weeks.  The  following  data  will  illus- 
trate the  rate  of  change : 


Sea-level 

Colorado  Springs 

Pike's  Peak  (14,110  feet). . . 

40  minutes  after  arrival 

Second  day 

Fourth  day 

Seventh  day 

Twenty-eighth  day 


Percentage  of  gases 
in  alveolar  air. 


COj. 


5.55 

6.54 

7.8 

7.52 

7.41 

7.21 

7.21 

6.63 


O.. 


14.08 
12.94 


11.38 
11.26 


11.98 
13.08 


Partial  pressure  of 
gases  in  alveolar  air. 


COa. 


39.6 
37.3 
32.2 
31.1 

30.7 


29.6 
27.4 


O,. 


100.4 
73.8 


47.1 
46.6 


49.0 
54.0 


156  AIE  SEEVTCE   MEDICAL. 

In  physiology  it  is  found  that  the  action  of  gases  within  the  body  is 
determined  by  the  pressure  and  not  by  the  percentage  of  gas.  The 
above  table  shows  that  the  percentage  of  alveolar  carbon  dioxide 
rises  with  the  altitude,  but  as  its  partial  pressure  is  determined  by  the 
barometric  pressure  we  find  that  there  is  a  fall  in  the  alveolar  carbon 
dioxide  partial  pressure  as  altitude  increases.  As  the  partial  pressure 
of  carbon  dioxide  in  the  alveolar  air  is  about  a  third  less  (about  27 
mm.  as  compared  with  40  mm.)  on  Pike's  Peak  than  at  sea  level,  it  is 
evident  that  the  alveolar  ventilation  during  rest  for  an  equal  produc- 
tion of  carbon  dioxide  is  about  30  per  cent  greater  than  on  Pike's 
Peak.  Actual  measurements  show  that  the  volume  of  air  breathed 
by  a  subject  on  Pil^e's  Peak  is  27  per  cent  greater  during  rest  in  bed, 
about  31  per  cent  greater  when  standing  at  rest,  about  50  per  cent 
greater  when  Avalking  at  the  rate  of  4-^  miles  per  hour,  and  100  per 
cent  greater  during  more  severe  exertion  than  for  similar  experiences 
at  sea  level.  An  increase  of  30  to  50  per  cent  in  the  air  breathed  when 
the  subject  is  at  rest  is  not  noticeable  subjectively.  During  hard 
work,  on  the  other  hand,  an  increase  of  50  per  cent  in  alveolar  venti- 
lation is  very  noticeable  since  panting  becomes  excessive  with  a  good 
deal  of  muscular  work.  During  hard  work,  even  at  sea  level,  the  depth 
of  breathing  is  about  maximal.  Hence  the  increased  alveolar  ventila- 
tion at  a  high  altitude  during  exertion  implies  a  corresponding  in- 
crease in  the  frequency  of  breath,  with  a  corresponding  increased 
sense  of  effort.  It  is  clear,  therefore,  that  at  the  high  altitudes,  such 
as  14,000  feet,  there  is  excessive  hyperpnea  on  exertion.  The 
hyperpnea  is  probably  about  three  times  greater  than  would  be  the 
case  with  a  corresponding  exertion  at  sea  level.  Walking  at  the  rate 
of  4  miles  an  hour  at  sea  level  would  cause  no  respiratory  inconven- 
ience, but  the  same  work  at  14,000  feet  causes  extreme  and  urgent 
hyperpnea.  Excessive  hyperpnea  on  exertion  persists  at  14,000  feet 
during  the  entire  sojourn,  but  it  becomes  less  marked  after  the  first 
day  or  two. 

During  inaction  the  breathing  at  high  altitude  is  ordinarily'  modi- 
fied only  in  depth.  The  rate  of  breathing  at  sea  level  varies  normally 
between  14  and  18  breaths  per  minute.  In  many  men  this  rate  also 
continues  at  an  altitude  of  41,000  feet.  During  exertion  the  rate 
must  increase  since  at  sea  level  for  a  given  exercise  the  breathing  is 
often  maximal.  It  follows,  therefore,  that  the  same  exertion  at  the 
high  altitude,  if  it  increases  the  total  ventilation  of  the  lungs,  can 
only  do  so  by  increasing  the  rate  of  breathing.  The  following  ob- 
servations made  on  Pike's  Peak  clearly  prove  the  above  statement: 
The  subject  had  breathed  when  in  bed  at  sea  level  at  the  rate  of  16.8 
breaths  per  minute,  when  on  Pike's  Peak  17.3;  on  standing  at  sea 
level  17  breaths  per  minute,  on  Pike's  Peak  20 ;  walking  at  the  rate  of 
4  miles  per  hour  at  sea  level  17.2  breaths  per  minute,  on  Pike's  Peak 


ATE  SERVrCE  MEDICAL.  157 

29;  and  at  the  rate  of  5  miles  per  hour  at  sea  level  20  breaths  per 
minute,  on  Pike's  Peak  36. 

To  explain  the  fall  in^  alveolar  carbon  dioxide  pressure  and  the 
increased  ventilation  of  the  lungs  at  high  altitudes  it  is  necessary  to 
consider  the  changes  that  occur  in  the  blood.    Greater  stress  was  laid 
by  Mosso  upon  the  diminished  carbon  dioxide  in  the  breath,  not  be- 
cause its  diminution  is  of  any  importance  in  the  breathing,  but  be- 
cause this  is  the  reflection  of  a  lowered  cajjbon  dioxide  pressure  in 
the  body  generally.     Want  of  carbon  dioxide  would,  other  things 
being  equal,  affect  the  affinity  of  the  blood  for  oxygen.     Decreased 
carbon  dioxide  alone  in  the  blood  would  increase  the  affinity  of  the 
blood  for  oxygen.     However,  with  the  increase  in  altitude  it  is  found 
that  the  affinity  of  tlie  blood  for  oxygen  remains  approximately  un- 
^.Itcred  in  spite  of  the  lower  carbon  dioxide  tension.     This  suggests 
that  as  one  ascends  the  carbon  dioxide  in  the  blood  is  replaced  by 
something  else  which  produces  an  equal  effect  on  the  affinity  of  the 
hemoglobin  for  oxygen.     A  study  of  the  dissociation  curve  of  the 
blood  made  by  Barcroft  at  various  altitudes  indicates  that  there  is 
an  increase  in  the  acid  radicals,  or  a  decrease  in  the  bases  of  the 
blcod.     The  higher  the  altitude  reached  the  more  marked  is  the 
acidosis,  but  at  any  gi^'en  altitude  the  acidosis  and  the  diminution 
of  carbon  dioxide  so  nearly  balance  each  other  that  the  reaction  of 
the  blood  remains  practically  constant.     Only  a  very  careful  study 
has  been  able  to  show  that  the  increase  of  acidity  is  slightly  in  excess 
of  the  loss  of  carbon  dioxide.     This  would  lower  the  affinity  of  the 
blood  for  oxygen  very  slightly;  but  at  the  same  time  the  change 
would  be  sufficient  to  give  the  increased  stimulation  to  the  respiratory 
center,  which  would  account  for  the  increased  ventilation  of  the 
lungs.     What  acid  is  responsible  for  the  acidosis  in  the  blood  at  high 
altitudes  has  not  yet  been  ascertained.     It  was  once  thought  that 
lactic  acid  appeared  in  the  blood  with  the  acclimatization  to  high 
altitude,  but  this  is  not  maintained  at  present.     It  may  be  that  there 
is  no  increase  of  acid  at  all,  but,  rather,  a  diminution  in  the  amount 
of  alkali  present.     The  fact  that  the  alkalinity   of  the  blood  is 
diminished  at  high  altitudes  was  first  demonstrated  by  Galeoti  in 
1903.     At  that  time  it  was  already  known  that  lactic  acid  is  pro- 
duced by  an  excessive  muscular  exertion,  as  a  consequence,  no  doubt, 
of  a  lack  of  oxygen  in  the  active  muscles,  and  this  suggested  that 
lactic  acid  is  formed  when  the  organism  experiences  the  oxygen 
want  at  high  altitudes.     But  the  excess  of  lactic  acid  formed  during 
muscular  exertion  disappears  again  within  an  hour,  together  with  its 
effect  on  the  alveolar  carbon  dioxide  pressure.     If  the  diminished 
alkali  of  blood  at  high  altitudes  were  simply  due  to  lactic  acid 
formed  in  excess,  we  should  similarly  expect  this  diminished  alka- 


158  AIR  SERVICE  MEDICAL. 

linity  to  disappear  and  appear  rapidly,  and  would  expect  similar 
marked  variation  in  the  alveolar  carbon  dioxide  pressure.  The  in- 
crease in  acid  in  the  blood  and  the  lowering  of  the  alveolar  carbon 
dioxide,  however,  require  days  to  develop.  Vezar  has  shown  that 
oxygen  want  increases  the  activity  of  the  kidneys,  which  suggests 
that  oxj'gen  want  so  affects  the  kidney  that  it  excretes  alkali  more 
freel}-.  It  certainly  looks  as  if  the  blood  and  the  breathing  changes 
were  due  to  some  adaptive  alteration  in  the  regulation  of  blood 
alkalinity.  "  The  fixed  alkalinity  of  the  bodj'-  as  a  whole,  including 
the  blood,  is  evidently  regulated  normally  by  the  action  of  the 
kidneys,  although  the  liver,  by  varying  the  amount  of  ammonia  in 
the  blood,  may  also  contribute  to  the  regulation.  A  slight  and 
gradual  adaptive  alteration  in  what  one  may  call  the  exciting 
threshold  of  alkalinity  for  the  kidneys  would  explain  the  reduced 
fixed  alkalinity  of  the  blood  in  acclimatized  pei*sons."  Tlie  above 
observations,  if  correct,  indicate  that  there  is  a  loss  of  reserve  alka- 
linity among  the  inhabitants  of  high  altitudes  which  may  place  the 
body  at  a  disadvantage  in  certain  pathological  conditions. 

OTHER  ALllTUDE   RESPIRATORY  OBSERVATIONS. 

Periodic  breathing  is  frequently  observed  among  newcomers  at 
ver}'  high  altitudes — the  type  ^'a^J■ing  in  different  persons.  It  may 
occur  in  groups  of  three  or  four  breaths,  each  succeeding  breath  being 
deeper  than  the  preceding  one  and  each  group  then  followed  by  a 
pause  in  breathing;  or  there  maj-  be  no  pause,  the  breaths  occurring 
in  groups  of  6  to  10  in  which  there  is  a  gradual  increase  in  depth  to 
the  mid-point  and  then  a  gradual  decrease.  The  periodic  breathing 
often  is  initiated  by  muscular  exertion  and  may  be  started  at  anj' 
time  by  a  few  forced  breaths  or  b}^  holding  the  breath  a  few  seconds. 
No  doubt  the  spontaneous  periodic  breathing  met  with  at  the  high 
altitudes  depends  upon  want  of  oxygen  in  that  it  has  been  shown 
that  it  may  be  abolished  by  the  administration  of  pure  oxygen.  Peri- 
odic breathing  disappears  in  the  majority  of  men  as  they  become 
acclimated  to  the  altitude. 

The  ability  to  hold  the  breath  is  decreased  at  high  altitudes.  It 
has  been  found  that  when  first  arriving  at  14,000  feet  men  may  be 
able  to  hold  the  breath  almost  as  long  as  at  a  low  altitude.  Day 
after  daj^,  for  some  time,  it  will  be  found  that  the  voluntary  effort 
of  holding  the  breath  becomes  greater  and  that  the  period  of  holding 
grows  shorter.  No  doubt  the  ability  to  hold  the  breath  decreases  as 
the  acidosis  of  the  blood  increases. 

It  is  a  popular  belief  that  high  altitudes  increase  the  size  of  the 
chest  and  the  vital  capacity.  Humboldt,  in  1799,  claimed  to  have 
observed  this  increase  in  people  of  the  Andes;  and  Williams  noted 
the  same  result  after  residence  in  a  high  moimtain  resort.     With 


AID   SEKVICE   MEDICAL.  159 

these  exceptions  all  observers  agree  that  for  the  majority  of  persons 
the  low  atmospheric  pressure  alone  does  not  increase  the  vital  ca- 
pacity. It  has  been  shown  that  the  enlargement  of  the  heaii  at  high 
altitudes  is  the  result  of  the  greater  demands  made  upon  that  organ 
during  physical  exertion.  If  the  chest  should  be  found  larger  among 
the  inhabitants  of  high  altitudes  it  likewise  may  be  explained  by 
the  increased. demand  made  upon  the  breathing  during  muscular 
effort.  The  immediate  effect  of  altitude  is  to  cause  a  slight  de- 
crease in  the  vital  capacity.  A  comparison  made  of  men,  at  a  low 
and  high  altitude,  indulging  in  outdoor  sports,  would  show  that  the 
vital  capacity  and  the  chest  measurements  are  siniilar.  Use  makes 
the  organ,  and  the  size  of  the  chest  depends  upon  the  demands  made 
in  breathing  hj  physical  exertion  during  the  period  of  growth. 

THE  OXTGEN  PRESSURE  OF  THE  ARTERIAL  BLOOD  AT  HIGH  ALTITUDES. 

The  problem  which  concerns  us  here  is  to  determine  the  forces  by 
which  oxygen  is  transported  from  the  alveolar  air  of  the  lungs  into 
the  blood.  With  increasing  altitudes  the  air  is  reduced  and  oxygen 
tension  becomes  lower  and  lower.  At  a  height  of  about  15,000  feet 
the  barometric  is  little  over  half  that  of  atmospheric  pressure  and  the 
oxygen  tension,  therefore,  only  about  11  per  cent  of  an  atmosphere. 
As  has  been  pointed  out,  the  presence  of  man  at  any  considerable 
altitude  necessitates  adjustment  on  his  part  so  that  the  persistent  un- 
diminished oxygen  requirement  of  the  body  can  be  satisfied  under 
the  enforced  changes  of  atmospheric  conditions.  Three  of  the  pos- 
sible means  of  providing  the  necessary  oxygen  have  already  been  dis- 
cussed. The  fourth  possibility  is  still  under  debate  among  physi- 
ologists. All  the  symptoms  of  altitude  sickness,  due  to  the  dimin- 
ished barometric  pressure,  depend  directly  or  indirectly  upon  the 
diminution  of  arterial  oxygen- pressure  and  the  consequent  imperfect 
aeration  of  the  arterial  blood  and  deficient  saturation  of  its  hemo- 
globin with  oxygen. 

The  passing  of  oxygen  from  the  alveolar  air  into  the  blood  of  the 
lung  capillaries  may  be  wholly  the  result  of  diffusion  of  oxygen,  in 
which  case  it  would  pass  from  a  place  of  high  to  one  of  low  pressure. 
If  oxygen  passes  from  the  alveoli  only  by  diffusion,  the  pressure  of 
oxygen  in  the  blood  will  always  be  less  than,  or  at  the  best  equal  to 
the  alveolar  oxygen  tension.  If  the  pressure  of  oxygen  in  the  blood 
is  under  certain  circumstances,  higher  than  that  of  the  alveolar  air 
there  can  be  no  doubt  that  forces  other  than  diffusion  must  come  into 
play.  This  would  necessitate  an  active  secretion  by  the  epithelial  cells 
of  the  lungs.  At  sea  level,  during  rest,  the  arterial  oxygen  pressure  is 
practically  identical  with  the  alveolar  oxygen  pressure.  The  Anglo- 
American  Pike's  Peak  Expedition  in  1911  made  a  careful  study  of  the 
arterial  oxygen  pressure  and  found  in  every  case  that  the  arterial  oxy- 


160  AIR  SERVICE   MEDICAL. 

gen  pressure  in  men  on  Pike's  Peak  was  much  above  the  alveolar  oxy- 
gen pressure.  The  average  excess  of  oxygen  pressure  in  the  arterial 
blood  was  35.8  mm. ;  the  mean  normal  resting  alveolar  oxygen  pressure 
52.5  mm. ;  the  arterial  oxygen  pressure,  therefore,  88.3  mm.  The  alveo- 
lar oxygen  pressure  at  sea  level  is  about  100  mm.  and  that  of  the  blood 
about  the  same.  At  sea  level  the  arterial  blood  is  96  per  cent  satu- 
rated with  oxygen,  while  on  Pike's  Peak,  if  the  changes  of  acclimati- 
zation are  well  established,  it  is  95  per  cent  saturated.  One  subject 
was  examined  within  an  hour  after  reaching  the  summit  of  Pike's 
Peak  by  railway.  His  face  had  a  distinctly  bluish  color  and  he  suf- 
fered somewhat  severely  from  mountain  sickness  during  the  ensuing 
24  hours.  At  this  time — the  time  of  the  experiment — his  arterial 
oxygen  pressure  was  52.7  millimeters,  or  only  7  millimeters  above 
the  alveolar  oxygen  pressure.  Three  days  later,  when  he  had  become 
acclimated,  feeling  perfectly  well  and  with  normal  color,  the  arterial 
oxygen  pressure  was  81.4  millimeters,  or  40.7  millimeters  above  the 
alveolar  oxygen  pressure.  These  results  are  very  striking  and  point 
consistently  to  the  conclusion  that  in  acclimatization  to  high  altitudes 
the  lungs  acquire  the  power  of  raising  the  arterial  oxygen  pressure 
by  actively  secreting  oxygen. 

Certain  indirect  evidences  support  this  theory  of  oxygen  secretion. 
It  was  found  on  Pike's  Peak,  on  saturating  the  blood  with  alveolar 
air  in  a  saturator,  that  the  blood  was  noticeably  dark  in  color  as  com- 
pared with  the  blood  when  drawn.  It  is  well  known  that  men  can 
live  and  work  at  higher  altitudes  than  that  of  Pike's  Peak.  In  the 
explorations  of  the  Duke  of  the  Abruzzi  in  the  Himalayas  he  and  his 
companions  climbed  to  an  altitude  of  24,580  feet;  the  atmospheric 
oxygen  pressure  saturated  in  inspiration  would  be  55.4  millimeters 
and  the  alveolar  oxygen  pressure  only  21  millimeters.  Blood  satu- 
rated with  alveolar  air  at  this  pressure  would  be  less  than  half  satu- 
rated with  oxygen,  which  is  the  percentage  found  in  the  arterial 
blood  of  animals  at  the  point  of  death  from  asphyxia.  Nevertheless, 
at  this  altitude  the  members  of  the  expedition  felt  well  and  were  able 
to  do  the  climbing  necessary  in  attaining  the  altitude.  The  recent 
advances  in  knowledge  as  to  the  blood  gases  and  the  physiology  of 
respiration  make  it  difficult  to  explain  by  the  simple  diffusion  theory 
the  reactions  above  quoted.  Haldane  and  his  colaborators  have 
found  that  at  sea  level  muscular  work  may  furnish  a  powerful  stimu- 
lus to  secretory  absorption  of  oxygen  by  the  lung  epithelia  tissue. 
Therefore  one  advantage  in  indulging  in  heavy  muscular  work 
would  be  to  train  the  lungs  in  oxygen  secretion. 

THE  VALUE  OF  THE  TACTORS  OF  ACCLIMATIZATION. 

The  acclimatization  to  oxygen  want  in  mountaineers  or  persons 
living  at  high  altitudes  is  evidently  attributable  to  four  factors: 


AIE  SEKVICE  MEDICAI..  161 

The  increased  breathing,  the  increased  percentage  of  hemoglobin, 
the  increased  rate  of  blood  flow,  and  the  increased  oxygen  tension  in 
the  blood,  the  result  of  increased  activity  of  the  lung  epithelium. 

There  are  varying  degrees  of  susceptibility  to  vrant  of  oxygen 
among  any  group  of  men  exposed  to  low  barometric  pressure.  With 
a  rapidly  falling  oxygen  pressure  some  persons  simply  become  blue 
and  lose  consciousness  without  the  adaptive  mechanisms  of  the  body 
making  any  evident  response.  Men  who  are  fortunate  enough  to 
possess  brain  centers  sensitive  to  oxygen  want  will  respond  quickly 
to  the  stimulus  of  a  lack  of  oxygen  and  either  escape  or  have  only  a 
mild  attack  of  mountain  sickness.  On  the  other  hand,  those  with  an  in- 
sensitive nervous  mechanism  will  fail  to  respond,  or  be  so  slow  in  doing 
so  that  a  period  of  altitude  sickness  must  be  expected.  This  sickness 
will  begin  to  wane  when  the  adaptive  changes  begin  to  be  manifest. 
There  are  marked  individual  differences  which  are  no  doubt  asso- 
ciated in  some  way  with  the  freedom  of  the  blood  supply  to  the  brain. 
Ordinarily  on  ascending  a  mountain  the  respiratory  adjustment 
occurs  first,  beginning  almost  at  once;  it  requires,  however,  several 
weeks  to  become  complete.  After  some  delay  the  blood  changes,  tTie 
increase  in  the  rate  of  blood  flow,  and  the  so-called  oxygen  secretion 
manifest  themselves.  The  order  of  their  onset  and  the  rapidity  of 
development  will  depend  on  the  physical  condition  of  the  individual 
and  the  sensitiveness  of  the  brain  centers  to  low  oxygen. 

There  is  at  the  start  a  rapid  increase  in  each  of  the  factors  in- 
volved, followed  by  a  more  gradual  continuation  of  the  effect  extend- 
ing over  some  weeks.  The  increase  in  the  rate  of  blood  flow  and  the 
oxygen  secretion  hj  the  lungs  are  developments  of  the  first  two  or 
three  days  spent  at  the  high  altitude.  The  blood  changes,  while 
rapid  during  the  first  few  days,  require  more  than  five  weeks  to  reach 
their  maximum  value.  The  changes  in  the  breathing,  the  blood,  and 
in  oxygen  secretion  are  of  a  permanent  character  and  will  not  di- 
minish with  a  prolonged  residence  at  the  high  altitude.  The  changes 
in  the  rate  of  blood  flow  are  of  a  less  permanent  character;  with  the 
acclimatization  the  pulse  rate  returns  somewhat  toward  the  sea-level 
values.  Undoubtedly  the  heart  is  under  a  greater  strain  during  the 
early  days  spent  at  a  high  altitude  than  later,  when  the  adaptive 
changes  have  been  completed.  Physical  fitness  usually  assures  an 
early  and  rapid  response  to  the  stimulating  effects  of  low  oxygen  at 
the  high  altitude.  Fatigue  and  other  debilitating  causes  delay  the 
response  and  make  the  individual  more  liable  to  an  attack  of  altitude 
sickness. 

The  longer  the  period  of  sojourn  at  a  high  altitude  the  more  perma- 
nently fixed  become  the  altitude  adaptive  changes.  This  fact  has 
been  proven  by  studies  on  the  after  effects  of  high  altitudes  in  those 
who  return  toward  sea  level.    If  the  sojourn  at  the  high  altitude  were 


162  AIB  SERVICE   MEDICAL. 

of  a  short  duration,  only  a  few  days,  on  returning  the  blood  is  re- 
stored almost  immediately  to  its  normal  composition.  The  breathing 
likewise  at  once  takes  on  the  normal  depth  and  rate.  After  a  so- 
journ of  five  weeks  on  Pike's  Peak  the  after  effects  on  descending 
were  shown  to  be  present  for  a  period  of  at  least  two  weeks.  At  the 
end  of  a  six  months  stay  at  the  same  altitude  the  percentage  of  hemo- 
globin, number  of  red  corpuscles,  total  volume  of  blood,  and  total 
oxygen  capacity  did  not  alter  at  once  and  were  at  least  10  weeks  in 
being  restored  to  the  low-altitude  values.  The  breathing  for  24  hours 
was  as  great  as  when  at  14,110  feet  and  then  slowly,  throughout  a 
period  of  10  weeks,  decreased  to  the  normal  for  the  lower  altitude. 
The  first  days  after  descending,  the  pulse  rate  was  about  10  beats  be- 
low the  normal  for  the  low  altitude,  but  later  accelerated  to  the  nor- 
mal for  the  particular  altitude. 

The  study  of  the  after  effects  indicates  that  the  aviator  remains  at 
the  high  altitudes  too  short  a  period  of  time  to  secure  permanent 
adaptive  reactions  which  increase  toleration  of  high  altitudes.  Re- 
peated experiments  in  pneumatic  chambers  and  with  carbon  monoxide 
occasionally  have  increased  in  some  men  the  ability  to  tolerate  low 
oxygen.  The  experience  in  aviation  indicates  that  the  changes  in 
altitude  during  flying  are  made  so  rapidly  that  the  compensating 
mechanisms  for  low  oxygen  are  overworked  to  a  greater  or  less  degi*ee, 
and  as  a  consequence  instead  of  securing  acclimatization  to  low 
oxygen  a  weakening  of  the  adjusting  mechanisms  occurs,  which  ren- 
ders the  flier  more  liable  to  an  attack  of  altitude  sickness. 

PHYSICAL   FITNESS    AND   THE   ABILITY    TO    WITHSTAND    HIGH    ALTITUDES. 

The  ability  to  endure  comfortably  and  well  high  altitudes  is  de- 
pendent upon  the  ease  and  the  quickness  with  which  the  adaptive 
responses  in  the  breathing,  the  blood,  and  the  circulation  take  place. 
An  explanation  of  the  difference  in  reaction  observed  among  the  mem- 
bers of  a  group  of  men  when  at  a  high  altitude  is  to  be  found  in  the 
degree  of  individual  physical  fitness.  In  persons  damaged  by  dis- 
ease, overwork,  unhygienic  living,  or  weakened  by  inactivity  and  by 
loss  of  sleep,  the  power  of  adjustment  is  as  a  rule  below  par.  The 
normal  equilibrium  of  the  body  is  so  nicely  adjusted  that  under  usual 
conditions  the  physiological  balance  is  largely  maintained  by  adjust- 
ments that  are  made  with  little  or  no  expenditure  of  energy.  There 
is  a  certain  range  of  greater  or  less  breadth  through  which  the  exter- 
nal factors  of  the  environment  may  be  varied  and  yet  be  met  by  an 
automatic  adjustment  of  the  physiological  processes  in  the  body 
which  will  preserve  the  vital  balance  of  the  mechanism.  But  beyond 
a  certain  point,  specific  for  each  organism,  changes  in  the  external 
conditions  will  necessitate  more  radical  alterations  which  will  tax 
the  compensating  mechanisms  to  the  utmost  capacity  in  order  to  pre- 


AIK  SERVICE   MEDICAL.  163 

vent  disaster.  Theoretically  the  organism  which  has  been  called  upon 
repeatedly  to  make  a  certain  kind  of  adjustment  will  be  the  one  most 
capable  of  responding  when  an  extraordinary  demand  is  made.  The 
unusual  demand  made  upon  the  organism  at  a  high  altitude  is  that 
of  supplying  the  requisite  amount  of  oxygen  to  the  tissues  from  an 
atmosphere  that  provides  oxygen  at  a  greatly  reduced  pressure.  An 
organism  that  has  alwa^^s  been  able  to  supply  its  oxygen  needs  with- 
out profound  or  costly  changes  because  the  demands  for  oxygen  have 
never  been  excessive  or  the  oxygen  supply  has  never  been  reduced 
will  most  likely  not  readil}'^  respond  when  it  meets  a  shortage  of 
oxygen.  In  the  everyday  experiences  of  life  there  arises  a  marked  in- 
crease in  the  demand  for  oxygen  during  physical  exertion.  Excessive 
exertion  may,  of  course,  call  for  so' much  oxygen  that  the  adjustments 
of  the  body  may  fail  to  provide  sufficient  quantity  for  complete 
combustion  in  the  muscles.  That  this  is  often  the  case  is  proven  by 
the  great  production  of  lactic  acid  during  physical  work.  Since 
physical  exertion  does  increase  the  demand  for  oxygen  it  is  to  be 
expected  that  the  organism  which  has  been  called  upon  to  do  physical 
work  frequently  will  have  acquired  marked  powers  for  compensating 
for  oxygen  want. 

Comparisons  made  of  animals  leading  a  muscularly  inactive  life 
with  those  of  a  closely  related  species  whose  mode  of  living  calls  for 
much  running  and  gi'eat  physical  endurance  show  certain  well- 
defined  differences  attributable  to  muscular  action  and  the  call  for 
oxygen.  It  has  been  found  that  the  active  animal  has  a  heart  which 
relatively  is  three  or  four  times  heavier  than  that  of  the  inactive 
animal.  Also  the  rate  of  the  heart  beat  is  much  slower — only  about 
a  third — the  rate  of  respiration  less,  the  depth  of  breathing  greater, 
and  the  percentage  of  hemoglobin  greater  in  the  active  than  in  the 
inactive  animal.  Furthermore,  the  flesh  of  the  active  animal  is 
darker  in  color,  due  to  the  presence  of  a  larger  amount  of  myohe- 
matin — the  substance  with  marked  affinity  for  oxygen.  These  differ- 
ences are  undoubtedly  adaptive  and  fit  the  organism  to  supply  the 
tissues  with  the  extra  amount  of  ox^-gen  required  during  exertion. 

The  adaptive  characters  found  in  physically  active  animals  are  very 
like  those  that  appear  in  the  body  of  man  when  he  follows  a  regular 
and  consistent  course  of  physical  training,  and  they  likewise  are 
characteristics  which  will  permit  the  individual  to  tolerate  well  high 
altitudes.  Comparisons  made  of  athletic  and  nonathletic  individuals 
show  that  the  athletic,  or  better,  the  physically  fit  persons  possess  cer- 
tain physiological  conditions  of  advantage  at  high  altitudes. 

In  the  physically  fit  the  daily  indulgence  in  physical  exercise  will 
be  found  to  have  increased  the  percentage  and  the  total  amount  of 

89118—19 12 


164  AIK  SERVICE   MEDICAL. 

hemoglobin  in  the  blood.  With  this  advantage,  if  he  goes  to  a  high 
altitude,  he  quickly  responds  to  the  stimulating  influence  of  oxygen 
shortage  by  throwing  into  the  circulation  the  reserve  supply  of 
corpuscles  and  by  further  concentration  of  the  blood.  Consequently 
the  tissues  are  supplied  with  blood  which  per  unit  of  volume  is  richer 
in  oxygen  than  it  would  be  if  the  hemoglobin  were  less  concentrated. 
In  the  untrained  man  there  is  less  hemoglobin,  and  the  changes  in- 
duced by  altitude  occur  so  slowly  that  he  will  most  likely  suffer  with 
altitude  sickness  because  of  oxygen  want. 

In  the  physically  well  trained  the  breathing  is  slow  and  deep,  while 
in  the  untrained  it  is  shallow  and  rapid.  Deep  breathing,  which  can 
be  cultivated  by  exercise,  but  not  satisfactorily  by  voluntary  atten- 
tion, ventilates  the  lungs  more  effectively  than  shallow  breathing; 
therefore  at  a  high  altitude  there  is  advantage  in  being  a  deep 
breather.  It  also  can  be  shown  that  the  breathing  of  the  physically 
fit  man  responds  quickly  and  well  to  the  high  altitude  demand  for 
more  oxygen,  while  in  the  untrained  it  will  be  slower  in  doing  so. 

At  sea  level  moderate  muscular  work  does  not  create  a  great  de- 
mand for  oxygen,  but  strenuous  and  prolonged  exertion  may  tax  the 
oxygen-providing  mechanisms  to  their  utmost  capacity.  In  order 
to  meet  this  increased  demand  for  oxygen  the  lungs  may  respond  by 
secreting  oxygen  into  the  blood.  Repeated  demands  for  oxygen  secre- 
tion would,  so  to  speak,  train  the  lung  epithelium  for  the  unusual 
work.  It  is  suggested  that  such  a  reaction  by  the  lungs  would  be 
valuable  when  one  ascends  to  high  altitudes,  in  that  the  lungs  would 
then  immediately  begin  to  secrete  oxygen.  Oxygen  secretion  is  in  the 
nonathletic  type  of  individual  acquired  only  after  several  days  of  res- 
idence at  a  hi^h  altitude,  but  in  the  vigorous  well-trained  man  it  prob- 
ably begins  almost  immediately. 

As  a  result  of  physical  training  the  heart  reduces  its  rate  of  beating 
and  is  less  sensitive  to  changes  in  posture  and  to  moderate  exertion. 
In  the  physically  fit  the  heart  rate  does  not  increase  much  on  standing, 
but  in  the  wearied  or  physically  stale  subject  it  increases  as  much  as 
44  beats  per  minute.  The  vasomotor  control  of  the  splanchnic  area 
in  man  experiences  a  change  of  adjustment  when  the  body  is  moved 
from  the  horizontal  to  the  upright  standing  position.  In  a  robust 
subject  the  splanchnic  vasotone  increases  and  the  blood  pressure  is 
raised  about  10  millimeters  of  mercury.  In  an  individual  weakened 
by  dissipation,  overwork,  lack  of  sleep,  etc.,  the  blood  pressure  tends 
not  to  rise,  but  to  fall.  Weakness  is  sometimes  shown  by  a  decrease 
in  blood  pressure  and  at  other  times  by  an  excessive  increase  in  the 
heart  rate. 

At  a  high  altitude,  especially  during  the  first  days  of  residence, 
any  physical  exertion  makes  a  greater  demand  on  the  heart  than  the 


AIB  SEEVICE   MEDICAL.  165 

same  amount  of  work  at  sea  level.  In  the  nonathletic  individual  the 
heart  reacts  excessively  as  a  result  of  work,  while  in  men  in  excellent 
physical  condition  the  reaction  at  a  high  altitude  is  less  and  the  strain 
on  the  heart  will,  therefore,  be  much  less.  A  trained  heart,  like  a 
trained  muscle,  works  more  smoothly  and  easily  than  the  untrained, 
and  therefore  endures  fatiguing  work  better  than  the  untrained  heart. 

Medical  experience  with  the  "  stale  pilot "  and  the  "  stale  athlete  " 
has  shown  that  as  a  man  becomes  stale  his  p;J^siological  condition  re- 
verts to  that  of  the  nonathletic  type  of  individual.  Staleness  is  rec- 
ognized by  an  increased  frequency  of  pulse,  which  is  also  poor  in 
volume  and  low  in  tension.  There  will  be  distress  on  slight  exertion, 
accompanied  by  a  rapid  rise  in  the  pulse  rate,  which  returns  only 
after  a  long  interval  to  its  former  rate.  The  breathing  also  fre- 
quently becomes  shallow  and  rapid,  and  the  extremities  become  poor 
in  color  and  cold  because  of  poor  circulation. 

Most  of  the  symptoms  reported  as  common  among  aviators  while 
flying  are  those  that  are  characteristic  of  mountain  sickness.  It  has 
been  shown  that  mountain  sickness  is  not  so  common  among  robust 
as  among  individuals  of  sedentary  habits  of  living.  We  may  venture 
to  conclude,  therefore,  that  the  man  who  is  in  the  "pink  of  condi- 
tion" as  a  result  of  consistent  and  common-sense  physical  training 
will  be  more  resistent  to  the  action  of  altitude  than  the  untrained  or 
the  physically  stale  man. 

Medical  experience  with  "  stale "  aviators  shows  a  type  known  as 
the  nervous  in  which  there  is  poor  muscular  control  over  balance 
movements,  fine  tremors  of  the  hands  and  eyelids,  greatly  increased 
reflexes,  loss  of  sleep,  nightmares,  and  apprehensive  starts  with 
slight  noise.  The  influence  of  high  altitudes  on  the  nervous  system 
has  not  been  carefully  studied,  but  there  are  those  who  believe  that 
in  persons  with  poor  compensation  and  an  unstable  nervous  system 
there  is  increased  irritability  or  hyperexcitability  which  may  mani- 
fest itself  in  motor,  sensory,  or  psychic  spheres,  or  in  a  combination 
of  them.  Associated  with  the  increased  excitability  there  is  in- 
creased rapidity  of  fatigue  which  finds  expression  in  muscular  weak- 
ness and  diminished  physical  endurance,  as  well  as  failure  in  adapt- 
ability and  power  of  concentration  mentally.  Such  persons  complain 
of  a  mental  unrest,  approaching  anxiety,  and  find  difficulty  in  carry- 
ing on  the  usual  mental  requirements  of  their  occupations.  Such  a 
condition  may  be  the  forerunner  of  a  simple  neurasthenia  or  a  more 
profound  neurosis. 

The  nervous  system  is  exceedingly  sensitive  to  oxygen  want.  It 
is  significant,  therefore,  that  in  the  nervous  system  arrangements  are 
provided  for  a  free  supply  of  oxygen.  The  lack  of  oxygen  at  high 
altitudes  is  felt  by  all  body  tissues,  but  especially  by  the  nervous 


166 


AIR  SERVICE   MEDICAL. 


tissues.  It  seems  to  be  established  that  there  is  an  irritability  of  the 
nervous  system  that  may  be  attributed  to  diminished  oxygen  supply 
by  reason  of  a  failure  on  the  part  of  certain  individuals  to  compen- 
sate adequately  to  lack  of  oxygen  when  at  the  high  altitude. 

Relation  of  altitude,  pressure,  and  oxygen. 


mm.  HO. 

Elevation. 

0,. 

mm.  HG. 

Elevation. 

0,. 

760            

Feet. 

0 

1,000 

2,000 

3,000 

4,000 

5,000 

6,000 

7,000 

8,000 

9,000 

10, 000 

11,000 

12,000 

13, 000 

14.000 

IS,  000 

Per  cent. 
20.96 
20.15 
19.38 
18.04 
17.93 
17.25 
16.60 
15.97 
15.37 
14.80 
14.25 
13.73 
13.23 
12.75 
12.28 
11.83 

412 

Feet. 
16,000 
17, 000 
18,000 
19,000 
20,000 
21,000 
22,000 
23,000 
24,000 
25, 000 
26,000 
27, 000 
28, 000 
29,000 
30,000 

Per  cent. 
11.39 

732           

397 

10.97 

704   

382 

10.56 

677         

368 

10  16 

651 

3.54 

9.78 

626         

341 

9.41 

602 

328 

9.05 

579         

315 

8.70 

557 

303 

8.35 

536         

290  

8.01 

516 

278 

7.68 

497           

206 

7.35 

478 

254 

7.03 

461         

242  

6.71 

444 

230 

6.40 

428 

In  order  that  the  reasoning  which  led  to  the  development  of  the 
rebreathing  apparatus  and  the  study  of  man  under  rebreathing  may 
be  understood,  it  will  be  necessary  to  insert  here  a  brief  statement 
concerning  our  knowledge  of  the  effects  of  high  altitudes.  It  has 
been  known  for  a  long  time  that  man  living  at  extremely  high  alti- 
tudes may  develop  what  is  popularly  known  as  "  mountain  sickness," 
during  which  he  exhibits  certain  definite  symptoms.  After  a  shorter 
or  longer  period  of  sojourn  at  the  high  altitude,  these  symptoms 
pass  away  and  acclimatization  takes  place.  During  the  last  40  years, 
but  more  particularly  the  last  18  years,  physiologists  have  been  care- 
fully investigating  "  mountain  sickness  "  and  the  adaptive  changes 
that  occur  in  the  body  of  man  and  animals  living  at  great  altitudes. 
There  has  come  from  this  study  almost  complete  agreement  of  the 
investigators.  There  is,  in  fact,  no  room  now  for  doubt  that  the  essen- 
tial cause  of  all  the  symptoms  of  altitude  sickness  and  the  adaptive 
changes  within  the  body  is  the  lack  of  oxygen,  which  is  the  result 
of  the  rarefaction  of  the  air  that  occurs  as  altitude  increases.  The 
fact  that  there  is  oxygen  want  at  high  altitudes  suggested  the  fact 
that  any  mechanism  that  would  permit  the  breathing  of  a  reduced 
amount  of  oxygen  could  be  used  to  test  the  ability  of  men  to  with- 
stand the  effects  of  low  oxygen.  The  rebreathing  apparatus  was 
designed  not  only  to  expose  man  to  low  oxygen  but  to  a  constantly 
decreasing  amount  of  oxygen.  A  description  of  the  apparatus  and 
the  method  of  use  will  be  found  elsewhere  in  this  report. 

In  order  that  oxygen  percentages  may  be  translated  into  altitudes, 
the  relation  of  altitude  and  oxygen,  as  well  as  altitude  and  pressure, 


AIE  SEBVIOE  MEDICAL. 


167 


are  shown  in  chart  1.  On  referring  to  the  12  per  cent  oxygen  line, 
it  will  be  observed  that  when  the  subject  of  experimentation  is  breath- 
ing 12  per  cent  oxygen,  he  is  physiologically  at  an  altitude  of  14,400 
feet,  and  when  breathing  10  per  cent  oxygen  the  equivalent  altitude 
is  19,400  feet. 

One  purpose  in  the  method  of  examining  aviators  by  rebreathing 
is  to  reproduce  the  gradually  decreasing  oxygen  tension  that  they 
will  experience  as  they  ascend  in  the  air.  A*  sudden  disturbance  of 
bodily  functions  usually  is  manifested  by  symptoms  of  illness.  The 
disturbance  brought  about  by  changes  of  altitude  and  by  low  oxygen 
cause  the  so-called  "  altitude  sickness."  Individuals  differ  greatly 
in  the  power  of  resistance.     Hence,  we  find  that  altitude  sickness 


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attacks  some  at  a  lower,  others  at  a  higher  altitude,  but  it  is  also 
certain  that  no  one  who  proceeds  bej'^ond  the  elevation — that  is,  the 
critical  line  for  him — escapes  the  malady.  An  elevation  of  10,000 
feet,  or  even  less,  may  provoke  it  in  some;  others  may  escape  up  to 
14,000  feet  or  even  17,000  feet;  while  only  a  few  possessed  of  un- 
usual resisting  power  can,  without  pronounced  symptoms,  venture 
upward  to  18,000  feet.  The  flier  himself  may  not  be  conscious  of 
the  symptoms  when  they  first  appear.  The  degree  of  illness  will  be 
determined  by  the  length  of  time  the  subject  is  exposed  to  oxygen 
want.  In  the  rebreathing  experiments  we  produce  artificially  a 
mild  attack  of  altitude  sickness.  The  percentage  of  oxygen  at  which 
the  symptoms  appear  will  indicate  the  altitude  at  which  similar 


168  ATR  SERVICE  MEDICAL. 

symptoms  may  be  expected  to  occur,  provided  the  length  of  time 
given  to  the  rebreathing  experiment  has  not  been  too  short. 
Throughout  rebreathing  experiments  attention  has  been  directed  to 
a  stud}''  of  the  pulse  rate,  the  arterial  blood  pressure  changes,  the 
character  and  the  volume  of  the  breathing,  and  to  the  color  changes 
in  the  skin  and  mucous  membranes.  It  is  well  to  recall  here  that  in 
an  attack  of  "  mountain  sickness  "  the  pulse  rate  is  always  accelerated 
and  the  systolic  and  diastolic  pressures  are  higher  than  in  normal 
life.  The  patient  may  feel  slightly  giddy  and  there  may  be  buzzing 
in  the  ears,  dimmed  sight,  and  fainting  attacks.  The  face  may  be 
cyanosed  and  the  eyes  look  dull  and  heavy.  In  some  degree  all  of 
these  conditions  may  occur  as  the  subject  undergoes  the  exposure  to 
low  oxygen  tension  during  a  rebreathing  experiment.  Many  of  the 
reactions  here  called  "  symptoms,"  which  occur  under  low  oxygen 

tension  at  high  altitudes  and  during  a  rebreathing  experiment,  are 
simply  compensatory  changes  by  which  nature  endeavors  to  keep  the 
tissues  abundantly  supplied  with  oxygen. 

II.— THE  PHYSIOLOGY   OF   REBREATHING  AND   AVIATION. 

The  physiological  observations  made  on  men  and  animals  living 
at  high  altitudes  or  under  reduced  atmospheric  pressures  show  clearly 
that  a  very  marked  process  of  adaptations  occurs  which  renders  the 
mechanism  capable  of  meeting  the  call  of  the  tissues  for  oxygen.  The 
aviator  must  also  be  able  to  adapt  himself  physiologically  to  altitude 
changes.  The  aviator  does  not  remain  at  high  altitudes  long  enough 
to  benefit  from  slow  adaptive  physiological  changes,  therefore  his 
body  must  be  capable  of  making  rapid  compensatory  changes  which 
will  provide  the  oxygen  needed  by  the  tissues.  He  must  be  able  to 
bear  abrupt  and  great  changes  in  atmospheric  pressure.  Without 
the  occurrence  of  some  one  or  more  definite  adaptive  physiological 
responses  to  provide  for  his  oxygen  needs  as  he  ascends,  his  life  and 
aeroplane  become  more  and  more  jeopardized  as  he  continues  to 
ascend. 

That  the  body  can  and  does  respond  to  the  demands  for  oxygen 
during  rapid  ascents  has  been  proven  by  laboratory  experiments  and 
the  experience  of  aviators  and  balloonists.  The  physiological  re- 
sponses that  are  definite,  like  those  experienced  by  the  mountaineer, 
are  an  increased  ventilation  of  the  lungs  and  a  more  rapid  blood  flow. 
In  a  few  men  a  concentration  of  the  blood  may  also  occur. 

It  has  been  clearly  established  that  the  essential  cause  of  the 
adaptive  changes  within  the  body  when  at  high  altitudes  is  the  lack 
of  oxygen,  which  is  due  to  the  rarefaction  of  the  air  that  occurs  as 
altitude  increases.  The  fact  that  there  is  this  oxygen  want,  suggested 
that  any  mechanism  that  would  permit  the  breathing  of  a  reduced 
amount  of  oxygen  could  be  used  to  test  the  ability  of  naen  to  with- 


AIR  SERVICE  MEDICIT..  1G9 

stand  high  altitudes.  The  rebreathing  apparatus  has  been  per- 
fected for  such  tests.  During  the  tests  the  subject  breathes  the 
air  in  the  tank.  He  sits  with  a  clip  placed  on  the  nose  and  with 
a  comfortably  adjusted  mouthpiece  in  the  mouth,  which  is  suitably 
connected  by  means  of  inch  tubing  with  light  automatic  valves.  He 
inhales  the  air  through  the  respiratory  valve  direct  from  the  tank  and 
exhales  through  the  expiratory  valve  into  a  cartridge  containing  an 
absorbent  for  carbon  dioxide.  The  exhaled*  air  is  thus  freed  from 
carbon  dioxide  as  it  is  returned  to  the  tank.  A  spirometer  compen- 
sates for  changes  in  volume  and  writes  a  record  of  the  respiration 
upon  the  revolving  drum  of  a  kymograph.  By  this  arrangement  the 
subject  continues  to  rebreathe  the  air  in  the  tank  from  which  he 
gradually  absorbs  oxygen.  As  the  percentage  of  oxygen  decreases, 
the  subject,  in  effect  physiologically,  is  slowly  ascending  to  higher 
altitudes.  The  volume  of  air  rebreathing  is  sufficient  to  require  be- 
tween 25  and  30  minutes  to  lower  the  amount  of  oxygen  to  8  or  7  per 
cent,  which  is  equivalent  to  altitudes  of  25,000  to  28,000  feet. 

A  COMPARISON  OF  THE  REBREATHING  TEST  AND  THE  DILUTION  TEST. 

p 

Comparisons  to  date  of  the  rebreathing  and  dilution  tests  upon  the 
same  individuals  show  a  marked  similarity  in  the  reactions  which 
occur  and  demonstrate  conclusively  that  the  adaptive  changes  occur- 
ring in  both  cases  are  due  to  low  oxygen. 

The  dilution  apparatus  ^  used  in  our  laboratory  is  an  arrangement 
whereby  it  is  possible  to  let  pure  atmospheric  air  or  a  mixture  of 
atmospheric  air  and  nitrogen  pass  into  a  breathing  chamber  and  ac- 
cordingly, at  will,  change  the  relative  proportions  between  atmos- 
pheric air  and  nitrogen.  This  permits  of  changing  the  partial  pres- 
sure of  oxygen  at  any  desired  rate,  thus  producing  the  same  effect  as 
if  the  partial  pressure  of  oxygen  were  reduced  by  mounting  in  the 
air. 

The  rebreathing  machine  is  an  apparatus  whereby  the  subject  re- 
breathes  a  specified  amount  of  air  from  a  tank,  thereby  causing  a 
gradual  and  progressive  decrease  of  the  oxygen.  The  CO2  of  the 
expired  air  is  removed  by  an  absorbent  and  therefore  is  not  a  tactor 
in  the  test. 

Both  tests  are  essentially  low  oxygen  tests,  as  the  nitrogen  and  CO2 
play  no  part  in  producing  any  of  the  adaptive  changes. 

The  similarity  and  parallelism  of  the  reactions  in  both  tests  upon 

the  same  individuals  are  marked. 

A  comparison  of  many  charts  showed  the  average  point  of  accel- 
eration of  the  pulse  to  be  the  same  in  both  the  Dilution  Test  and  the 
Eebreathing  Test.  Also  the  limits  of  compensation  for  the  systolic 
and  diastolic  were  the  same  in  both.    A  fall  in  the  systolic  at  a  cer- 

*  Sef!  Jleports  of  the  Air  Medical  Investigation  Committee,  No.  2,  England. 


170  AIB  SERVICE   MEDICAL. 

tain  percentage  of  oxygen  in  the  Rebreathing  Test  was  almost  invari- 
ably accompanied  by  a  fall  in  the  systolic  at  the  same  percentage  of 
oxygen  in  the  Dilution  Test.  The  same  was  true  of  the  pulse  rate 
and  diastolic  pressure. 

Throughout  rebreathing  experiments  physiological,  psychological, 
and  other  observations  are  made  on  the  subject  of  the  test.  By  the 
physiologist,  the  rate  and  per  minute  volume  of  respiration,  pulse 
frequency,  systolic  and  diastolic  arterial  pressures  are  studied  for 
each  candidate  tested  and  have  been  found  to  give  valuable  evidence 
as  to  when  he  first  responds  to  the  reduction  in  oxygen  and  as  to  the 
efficacy  of  his  compensatory  reaction.  Some  men  are  sensitive  to 
oxygen  want  and  compensate  in  their  breathing  and  circulation  of 
the  blood  so  that  they  endure  as  low  as  6  per  cent  of  oxygen.  Others 
fail  to  compensate  in  one  or  both  of  these  mechanisms  or  compensate 
inadequately  and,  therefore,  can  not  endure  so  low  an  oxygen  per 
cent.  All  gradations  between  failure  to  compensate  and  adequate 
compensation  down  to  6  per  cent  of  oxygen  have  been  found  among 
the  men  examined  under  the  low  oxygen  of  the  rebreathing  tests. 
From  thfe  data  obtained  during  the  rebreathing  test  it  becomes  pos- 
sible to  determine  approximately  the  maximum  altitude  to  which 
the  aviator  may  safely  ascend. 

THE  BREATHING  WHEN  UNDER  THE  ACTION  OF  PROGRESSIVE  DECREASE  IN 
I  THE  OXYGEN  SUPPLY. 

The  character  of  the  breathing  undoubtedly  has  an  important 
bearing  on  the  ability  of  men  to  endure  at  high  altitudes.  The  shal- 
low breather  is  at  a  greater  disadvantage  than  the  man  who  breathes 
deeply  when  under  the  influence  of  low  oxygen.  In  breathing  a 
part  of  the  fresh  air  remains  in  the  nose,  pharynx,  larynx,  trachea, 
and  bronchial  tubes  and  is  emptied  out  again  at  the  beginning  of  the 
next  expiration  in  an  almost  unchanged  condition,  without  having 
actually  mingled  with  the  air  in  the  alveoli  of  the  lungs.  In  shallow 
breathing,  therefore,  only  a  comparatively  small  amount  of  the  fresh 
air  gets  past  this  so-called  dead  space  to  mingle  with  the  air  in  con- 
tact with  the  blood  vessels  of  the  lungs.  The  deeper  the  breathing 
the  greater  will  be  the  amount  of  fresh  air  that  reaches  the  aveoli 
of  the  lungs  and  hence  the  greater  will  be  the  supply  of  oxygen  for 
the  body  tissues. 

The  men  examined  have  shown  rates  of  breathing  when  sitting 
that  ranged  between  14  and  25  breaths  per  minute.  Between  40  and 
50  per  cent  breathed  at  the  rate  of  18  and  19  breaths  per  minute. 
The  per  minute  volume  of  breathing  ranged  between  7  and  12.5 
liters,  with  the  majority  between  8.5  and  9  liters.  The  average  tidal 
volume  of  air  breathed  was  500  cubic  centimeters  for  the  group, 
while  the  extre-nes  were  360  and  630  cubic  centimeters,  respectively. 


DREYER  LOW  OXYGEN  APPARATUS. 


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41 


AIE   SERVICE  MEDICAL.  171 

The  smaller  volumes  of  tidal  air  were  found  among  subjects  who 
breathed  most  frequently.  Thus  one  man  who  breathed  24  times 
per  minute  had  a  tidal  air  volume  of  375  cubic  centimeters,  while 
another  whose  rate  was  14  per  minute  had  a  tidal  air  volume  of  620 
cubic  centimeters.  A  sIoav,  deep  breathing  will,  as  a  rule,  introduce 
more  fresh  air  into  the  alveoli  of  the  lungs  than  the  shallow,  rapid 
type  of  breathing. 

As  the  percentage  of  oxygen  gradually  decreases  during  a  re- 
breathing  test  there  occurs  a  marked  respiratory  response  to  the 
lessening  oxygen  tension  which  increases  the  amount  of  air  breathed 
per  minute.  This  increase  in  the  lung  ventilation  in  a  few  men 
begins  with  the  first  decrease  in  the  oxygen  percentage  of  the  air 
breathed  and  is  a  gradual  proportional  increase  in  inverse  ratio  with 
the  reduction  in  oxygen.  Over  50  per  cent  of  the  men  examined  gave 
the  first  respiratory  response  between  16  and  14  per  cent  of  oxygen. 
Twenty-five  per  cent  responded  first  at  a  lower  oxygen  tension,  while 
a  small  number  of  men  gave  no  respiratory  response  to  the  decrease 
in  available  oxygen.  The  increase  in  lung  ventilation  is  for  the 
higher  percentage  of  oxygen  only  slight,  but  usually  becomes  more 
pronounced  when  the  available  oxygen  has  been  decreased  to  between 
12.5  and  9  per  cent.     ( See  charts  1-6. ) 

The  rate  of  breathing  for  many  men  remain  unchanged  throughout 
the  rebreathing  test.  The  majority,  however,  show  an  increase  of 
from  two  to  four  breaths  per  minute  at  between  8  and  6  per  cent 
of  oxygen.  A  few  of  the  men  examined,  shown  by  other  tests  to  be 
somewhat  physically  stale,  increased  the  frequency  of  breathing 
enormously.  Thus  one  subject,  with  a  frequency  of  22  when  sitting 
quietly  breathing  atmospheric  air,  breathed  43  times  per  minute 
at  8.5  per  cent  of  oxygen. 

The  amount  per  minute  volume  increase  in  the  breathing  during 
a  rebreathing  test  differs  with  individuals.  The  majority  of  men 
examined  show  at  per  centages  of  oxygen  between  8  and  0  per  cent 
an  increase  of  5.5  liters  over  the  volume  breathed  at  the  beginning 
of  the  experiment.  This  increase  gives  for  the  average  man  a  total 
volume  of  breathing  per  minute  of  approximately  14  liters  at  oxygen 
tensions  corresponding  to  an  altitude  of  25,000  feet.  The  total  per 
minute  volume  of  air  breathed  has,  in  exceptional  cases,  been  as 
great  as  26  and  37  liters  of  air  at  oxygen  tensions  corresponding  to 
from  25,000  to  28,000  feet. 

It  is  the  depth  of  breathing  which  ordinarily  is  increased  by  low 
oxygen.  The  vast  majority  of  subjects  show  an  increase  in  depth 
of  breathing  of  from  20  to  128  per  cent  when  under  8.5  to  6  per  cent 
oxygen.  The  volume  of  each  breath  in  these  men  if  found  to  range 
between  600  and  1,260  cubic  centimeters,  while  for  the  same  subjects 
when  sitting  quietly  breathing  atmospheric  air  the  tidal  volume  is 
found  to  range  between  360  and  630  cubic  centimeters. 


172  AIR  SERVICE  MEDICAL. 

A  good  respiratory  reaction  to  the  gradual  decrease  in  the  oxygen 
of  a  rebreathing  test  will  be  manifest  in  a  slight  increase  in  the 
depth  of  breathing  which  begins  at  16  or  15  per  cent  oxygen  and 
continues  to  progressively  increase  slightly  and  gradually  until  12.5 
to  9  per  cent  of  oxygen.  From  these  percentages  down  to  8.5  and  6 
per  cent  of  oxygen  the  total  per  minute  volume  of  breathing  increases 
much  more  rapidly  and  the  frequency  of  breathing  may  also  then 
increase  to  from  two  to  five  breaths  per  minute.  A  total  per  minute 
increase  of  at  least  5.5  liters  should  occur  at  the  lower  percentages 
of  oxygen.  The  increase  in  the  depth  of  breathing  which  occurs 
under  low  oxygen  more  effectively  ventilates  the  alveoli  of  the  lungs 
and,  therefore,  raises  the  alveolar  oxygen  tension  above  that  which 
would  be  present  if  the  breathing  remained  unchanged.  Such  an 
increase  in  alveolar  oxygen  permits  the  blood  to  be  more  thoroughly 
saturated  with  oxygen,  and  consequently  the  subject  can  endure  a 
lower  oxygen,  which  is  equivalent  to  a  higher  altitude. 

Some  men  have  repeatedly  been  under  observation,  and  most  of 
those  reacted  very  much  the  same  each  time  when  subjected  to  low 
oxygen.  Thus  one  man  who  endured  low  oxygen  unusually  well  in 
a  series  of  seven  tests  averaged  an  increase  of  6.5  liters  in  his  breath- 
ing when  breathing  7  per  cent  of  oxygen.  Ano^er  subject,  who 
invariably  suffered  when  under  the  influence  of  low  oxygen,  in  a 
series  of  five  tests  during  a  period  of  eight  days  had  an  average 
increase  of  only  3.3  liters  in  lung  ventilation. 

When  the  per  minute  volume  of  breathing  fails  to  increase  as  the 
amount  of  oxygen  inhaled  decreases,  or  when  it  increases  only 
slightly — 1  or  2  liters — the  lung  ventilation  is  sufficient  and  the 
subject  will  be  found  unable  to  tolerate  as  low  a  tension  of  oxygen 
as  the  man  whose  breathing  gradually  deepens  as  the  available  oxy- 
gen decreases.  Only  a  few  men  have  failed  to  show  a  respiratory 
response  to  low  oxygen,  and  none  of  these  have  tolerated  well  such 
low  oxygen  as  10  to  9  per  cent.  Men  whose  respiratory  center  is 
insensitive  to  oxygen  want  either  fail  to  show  an  increase  in  the 
breathing  or  are  slow  in  doing  so,  and  in  either  case  there  would  be 
poor  toleration  of  high  altitudes. 

An  occasional  subject  has  been  examined  whose  breathing  re- 
sponded well  at  first,  but  later,  when  the  percentage  of  oxygen  was 
low,  suddenly  began  to  breathe  less.  When  this  happened  fainting  or 
unconsciousness  quickly  followed.  One  subject  in  three  tests  sepa- 
rated by  intervals  of  several  days  suddenly  showed  a  decrease  in  his 
breathing  when  at  10  per  cent  of  oxygen.  He  fainted  the  first  time 
and  was  only  saved  from  doing  so  the  others  by  being  returned  at  once 
to  atmospheric  air. 

THE  CIKCtTLATION  WHEN  UNDER  A  DECREASING  OXYGEN  SUPPLY. 

The  rate  of  flow  and  the  amount  of  oxygen  passing  from  the  blood 
to  the  tissues  depends  on  the  difference  between  the  pressure  of  oxygen 


AIR  SEEVICi:   MEDICAL.  173 

in  the  blood  and  in  the  tissue.  The  higher  the  oxygen  pressure  in  the 
blood  the  greater  will  be  the  amount  of  oxygen  passing  from  the 
blood  of  the  capillaries  into  the  tissues.  In  active  tissues  the  oxygen 
tension  is  always  low.  It  is  usually  supposed  that  there  is  no  oxygen 
pressure  at  all  inside  the  cells.  The  dissociation  of  oxygen  from  the 
hemoglobin  occurs  with  great  rapidity  and  is  greatest  where  the 
differences  in  pressure  are  greatest.  It  follows,  therefore  that  when 
the  blood  flows  more  rapidly  through  the  ca-piliaries  of  a  tissue  more 
oxygen  will  be  made  available  than  if  it  flows  slowly.  At  hio-h  alti- 
tudes, or  under  low  oxygen,  the  blood  is,  at  first  at  least,  less  saturated 
with  oxygen  than  at  low  altitudes.  Therefore,  if  the  blood  contains 
less  oxygen  an  increase  in  the  rate  of  blood  flow  through  the  capil- 
laries would  be  a  means  of  providing  the  tissues  with  the  oxyo-en  de- 
manded for  their  activity.  An  increased  rate  of  blood  flow  has  been 
demonstrated  in  men  living  at  high  altitudes  and  is  undoubtedly  one 
of  the  first  of  the  adaptive  or  compensatory  changes  observed  in  the 
rapid  ascents  made  by  the  aviator. 

Circulator}^  observations  made  on  Pike's  Peak  (14.110  feet)  indi- 
cated that  the  increase  in  the  rate  of  blood  flow  w^s  the  result  of  a 
greater  frequency  of  heart  beat  and  a  dilatation  of  Ihe  arterioles. 

A  study  of  the  pulse  rate  during  exposure  to  lo\\^  oxygen  should 
therefore,  give  a  definite  indication  of  the  sensitiveness  of  the  oro"an- 
ism  to  low  oxygen.  We  have  found  the  pulse  rate  tob^  a  trustworthy 
indicator  of  oxygen  want  provided  care  is  taken  at  the  beginning  of 
a  low  oxygen  or  rebreathing  experiment  to  have  the  subject  calm  and 
quiet.  Excitement  pr  anxiety  may  give  a  higher  iiitial  pulse  rate 
which  will  obscure  the  beginning  of  the  oxygen  wan  response. 

Throughout  the  rebreathing  test  the  candidate's  pise  is  counted 
for  a  period  of  20  seconds  each  minute.  The  systob  and  diastolic 
blood  pressures  are  determined  every  other  minute  urino-  the  first 
part  of  the  test  and  every  minute  after  the  oxygen  ha  been  reduced 
to  approximately  11  per  cent.  The  rate  of  heart  beat  hs  been  found 
to  accelerate  in  a  few  men  at  17.5  per  cent  oxygen  (500  feet).  In 
one  group  of  TO  men  the  accelerations  began  as  follows 

1  per  cent  began  to  react  between  7,000  and  8,000 

feet 16. 0-15.  5  jr  cent  oxygen. 

12  per  cent  began  to  react  between  8,000  and  9,000 

feet 15.  5-14. 9  ir  cent  oxygen. 

20  per  cent  began  to  react  between  9,000  and  10,000 

feet 14.  &-14.  2  p  cent  oxygen. 

14  per  cent  began  to  react  between  10,000  and  11,000 

feet 14. 2-13.  7  pcent  oxygen. 

23  per  cent  began  to  react  between  11,000  and  12,000 

feet 13.  7-13.  2  pe:ent  oxygen. 

20  per  cent  began  to  react  between  12,000  and  13,000 

feet 13.  2-12.  7  pe^nt  oxygen. 

6  per  cent  began  to  react  between  13,000  and  14,000 

feet —  13. 7-12. 2  per.nt  oxygen. 


174 


AIB  SEBVICJE   MEDICAL, 


Legend  •«*— 0,,%v 

-•  Diast.  B.  P- 


•Ilium*'  Pulse 

Pulse  Pressure 


•  Resp.  in  decil.  per  min. 

Accom.  in  mm. 


•  ...•Sysfc  HTP 
Convergence  in  mm. . 


Age  25  years,  10  months. 

This  Is  almost  record  run  for  low  percentage  reached,  and  preservation  of  efficiency 
practically  uniiAlred  until  the  very  last.  Pulse  rather  high  from  the  start,  as  is  often 
the  case  in  suipts  who  compensate  particularly  well,  and  both  pulse  and  blood  pres- 
sure show  somisychic  influence  at  the  start.  During  the  course  of  the  test  there  is  a 
typical  modera/rise  in  pulse  and  systolic  pressure  and  a  gradual  tendency  downward 
of  the  diastoliressure.  No  suggestion  of  circulatory  exhaustion.  Bated  AA,  a  par- 
ticularly good/bJect. 


AIR  SEEVICE   MEDICAL.  175 

The  increase  in  heart -beat  frequency  is  at  first  slight,  only  from  one 
to  three  beats,  but  as  the  oxygen  percentage  decreases  a  greater  in- 
crease in  rate  is  likely  to  occur  with  each  decrement  in  oxygen.  A 
very  marked  acceleration  usually  occurs  when  the  oxygen  has  fallen 
to  between  13  and  9  per  cent.  In  some  men  after  the  beginning  of 
the  more  rapid  increase  in  acceleration  a  steady  increase  in  rate  occurs 
down  to  even  6.5  or  6  per  cent  oxygen,  while  in  others  after  a  period 
of  rapid  acceleration  the  amount  of  acceleration  becomes  less  with 
each  decrease  of  1  per  cent  in  oxygen.  The  last  condition  suggests 
that  the  power  to  compensate  has  about  reached  its  maximum.  Some 
men  at  first  react  with  a  good  acceleration  in  rate  but  soon  reach  a 
rate  beyond  which  there  will  be  no  further  response,  even  though  the 
oxygen  percentage  continues  to  be  lowered.  In  such  cases  after  hold- 
ing at  a  fixed  rate  for  a  while  the  heart  suddenly  begins  to  slow,  a 
sure  indication  that  the  limit  of  endurance  has  been  reached. 

A  total  increase  of  from  15  to  40  beats  in  the  heart  rate  during  a 
rebreathing  test  in  which  the  oxygen  is  lowered  to  between  7.5  and 
6.5  per  cent  constitutes  a  good  reaction  to  oxygen  want.  A  failure  to 
respond  by  an  acceleration  in  heart  beat  to  lowered  oxygen  either 
means  inability  to  react  to  the  low  oxygen  of  high  altitudes  and  early 
failure  or  it  may  mean  that  sufficient  compensation  is  secured  by 
increased  breathing  or  blood  concentration,  or  both.  Our  experience 
indicates  that  the  failure  to  respond  is  associated  with  poor  toleration 
of  low  oxygen.  An  acceleration  in  heart  rate  of  more  than  40  beats — 
50  to  70  have  been  observed — throws  too  great  a  burden  on  the  circu- 
latory mechanism  and  occurs  only  in  men  who  do  not  tolerate  well 
low  percentages  of  oxygen.  In  such  men  other  compensatory  reac- 
tions may  fail  to  occur.  So  far  as  the  response  in  pulse  rate  to  de- 
creasing oxygen  is  concerned  it  therefore  becomes  possible  to  rate  the 
reactions  as  poor,  good,  and  excessive.  A  poor  or  an  excessive  heart 
response  should  disqualify  the  candidate  for  very  high  altitudes ;  he 
should  only  ascend  to  moderate  heights. 

A  delay  in  the  first  appearance  of  acceleration  of  the  heart  rate 
may  be  due  to  an  insensitive  cardiac  brain  center  and  an  early  re- 
sponse may  indicate  a  mechanism  very  sensitive  and  responsive  to 
any  decrease  in  available  oxj^gen.  It  should  be  borne  in  mind,  how- 
ever, that  while  ordinarily  there  is  an  early  acceleration  in  the  heart 
rate,  a  delay  may  be  due  to  the  efficiency  of  other  methods  of  com- 
pensating to  the  stimulus  of  oxygen  want. 

The  determination  of  systolic  and  diastolic  arterial  blood  pressures 
show  whether  the  vasomotor  mechanism  responds  to  the  stimulus  of 
oxj'gen  want  in  an  adequate  manner  for  maintaining  the  increase  in 
the  rate  of  blood  flow  and  at  the  same  time  whether  the  heart  is  com- 
pelled to  work  against  an  increased  resistance.  They  further  give  an 
index,  the  pulse  pressure,  of  the  volume  of  ventricular  output. 


176  AIR  SERVICE  MEDICAL. 

COLOR  CHANGES  DURING  REBREATHING. 

The  skin-color  changes  also  give  a  satisfactory  means  of  judging 
the  reaction  of  the  subject  to  low  oxygen.  The  normal  condition  is  a 
gradual  development  of  cyanosis.  In  a  healthy  reaction  this  is  de- 
layed in  its  onset ;  in  a  poor  case  it  appears  early  and  becomes  much 
more  pronounced  as  rebreathing  continues.  Some  men  do  not  show 
a  well-defined  cyanosis  but  become  pale  and  deathlike  in  color.  This 
is  not  a  good  reaction  and  may  be  found  associated  with  other  symp- 
toms— heart  and  circulatory — which  disqualify  for  high  altitudes. 

THB  DURATION  OF  THE  REBREATHING  TEST. 

The  length  of  time  taken  to  reach  a  low  oxygen  in  the  rebreathing 
test  will  profoundly  alter  the  ability  to  endure  extremely  low  per- 
centages. If  the  oxygen  is  lowered  rapidly  the  candidate  compen- 
sates to  a  lower  percentage  than  is  possible  where  the  rate  of  decrease 
in  the  oxygen  is  slower.  Three  rebreathing  experiments  made  on  the 
same  subject  illustrate  the  condition.  The  volume  of  air  was  so  small 
for  the  first  test  that  in  23^  minutes  the  oxygen  was  lowered  to  6.3 
per  cent,  at  which  the  subject's  power  of  compensation  failed.  The 
next  day  rebreathing  a  larger  volume  of  air  for  38  minutes  he  com- 
pensated to  7  per  cent  only.  On  the  following  day  in  a  test  of  85 
minutes'  duration,  compensation  failed  at  8.7  per  cent  of  oxygen. 
Individual  differences  will  be  found;  in  some  men  time  has  a  more 
profound  influence  than  in  others.  Thus  another  subject  compen- 
sated in  a  test  of  36  minutes  down  to  7.5  per  cent  and  in  one  of  90 
minutes  to  8  per  cent  of  oxygen.  Therefore,  when  testing  ability  to 
endure  low  oxygen,  some  allowance  must  be  made  for  the  time  taken 
to  reach  a  given  percentage.  -If  each  of  two  men  tolerate  down  to  7 
per  cent  oxygen  but  one  is  carried  down  in  20  and  the  other  in  40  min- 
utes, the  one  who  endures  for  40  minutes  will  have  the  better  power  of 
compensation. 

Control  tests  have  been  conducted  in  the  pneumatic  or  low-pressure 
chamber  to  determine  the  reliability  of  the  rebreathing  test.  A  sub- 
ject was  first  under  observation  in  a  rebreathing  test  and  again  on  the 
following  day  taken  into  the  low-pressure  chamber  for  similar  ob- 
servations, while  the  pressure  was  lowered  at  the  same  rate  that  the 
oxygen  had  been  absorbed  in  the  rebreathing  test.  The  breathing, 
pulse  rate,  and  blood  pressures  reacted  about  the  same  in  each  experi- 
ment. In  order  that  a  comparison  might  be  made  of  the  breathing 
under  the  two  conditions,  the  alveolar  air  was  analyzed  from  time  to 
time  during  each  kind  of  test.  A  fall  in  the  alveolar  carbon  dioxide 
and  oxygen  pressure  occurred  in  both  experiences.  The  average 
amount  of  fall  for  eight  men  at  the  per  cent  of  oxygen  or  pressure 
corresponding  to  20,000  feet  was  for  carbon  dioxide  during  rebreath- 


AIE  SEKVICE   MEDICAL.  177 

ing  8.5  millimeters  and  low  pressure  9.3  millimeters;  for  the  oxygen 
in  rebreathing  66.2  millimeters  and  low  pressure  68.8  millimeters. 
These  figures  show  that  the  increase  in  the  breathing  and  lung  ventila- 
tion was  about  the  same  under  the  two  different  low-oxygen  experi- 
ences. The  pulse  rate  also  was  found  to  begin  to  accelerate  at  about 
the  same  time  in  each  kind  of  test  and  to  accelerate  in  equal  degree. 
These  and  other  physiological  observations  made  on  men  undergoing 
the  rebreathing  test  or  under  decreasing  atnlospheric  pressure  prove 
that  the  same  compensations  are  used  by  the  body  in  each,  and  these 
we  laiow  are  the  adjustments  made  to  the  influence  of  oxygen  want. 

In  the  optimum  type  of  response  to  the  low  oxygen  of  the  rebreath- 
ing test  the  systolic  pressure  remains  unchanged ;  that  is,  it  holds  on 
a  level,  until  the  oxygen  has  been  lowered  to  between  14  and  9  per 
cent  after  which,  as  the  oxygen  is  further  lowered,  it  gradually  rises, 
or  there  may  occasionally  occur  a  gradual  rise  in  the  systolic  pressure 
beginning  with  the  first  increase  in  heart  rate  (see  chart  3).  This 
rise  in  pressure  is  ordinarily  to  from  15  to  20  mm.  Hg.  Other  sub- 
jects who  appear  to  have  tolerated  low  oxygen  well,  even  to  as  low  as 
6.5  per  cent  of  oxygen,  have  had  a  systolic  pressure  which  held  at  the 
normal  (see  chart  2). 

A  rise  in  the  systolic  pressure  of  more  than  30  mm.  Hg. — iO  to  60 
mm.  have  been  observed — is  very  likely  due  to  a  vasomotor  failure  to 
respond  with  a  dilatation  of  the  arterioles.  Such  conditions  will  lead 
to  overwork  by  the  heart  and  may  result  in  early  circulatory  failure. 

There  are  other  conditions  of  systolic  pressure  that  are  occasionally 
found  in  men  undergoing  the  rebreathing  test.  A  small  percentage 
of  subjects  examined  had  a  fall  in  the  systolic  pressure  which  began 
about  the  time  the  pulse  rate  started  to  accelerate  and  continued  to  de- 
cline throughout  the  test.  Such  men  have  not  tolerated  the  extremely 
low  percentages  of  oxygen  that  men  of  the  optimum  type  of  response 
have  endured. 

A  large  percentage  of  subjects  have  shown  a  sharp  and  sudden  fall 
in  the  systolic  pressure  at  low  percentages  of  oxygen.  This  fall  if 
allowed  to  continue  will  lead  to  fainting.  The  subject  recovers  his 
normal  pressure  at  once  if  he  is  returned  to  atmospheric  air. 

The  best  condition  in  the  response  of  the  diastolic  pressure  to  a  de- 
creasing oxygen  supply  consists  in  an  unchanged  or  slightly  increased 
pressure  throughout  the  test.  Many  men  show  a  gradual  well-con- 
trolled fall  in  the  diastolic  pressure  (see  charts  5  and  6)  during  the 
terminal  period  when  the  systolic  pressure  is  rising.  Such  a  fall  in 
the  diastolic  pressure  if  it  occurs  slowly  and  is  not  great  constitutes  a 
fairly  good  reaction  to  extreme  oxygen  want  and  can  be  explained  as 
a  vasomotor  dilatation  which  occurs  in  order  to  protect  the  heart 
against  the  rising  systolic  pressure.  In  the  optimum  type  of  response 
to  low  oxygen  the  terminal  fall  in  the  diastolic  pressure  may  not 


178 


AIR  SEEVIOE  MEDICAL. 


Legend.  ^ -—0.^% 

•— •  Diast.  B.  P. 


^tifii  till  ^ 


Pulse  \  (•• 

Pulse  Pressure 


Resp.  in  deciT.  per  itan. 
Accom.  in  mm. 


•-...# 'SysL  B.  P 
Convergence  in  mm.'- 


200 


ggiiigail^ 


%.( 


nil  ^i!:  iib  iiU  ipg.  rtk  Jiji  ^ii.  41:^  £;^  ji^L  i^^^ 


C  7^8  »  10  IX  12  18  14  15  16  17  18  19  30  31  33  23  24  35  28  27,28  20  30  81  32  83 

Chart  3 


n     n    n 

TIME  IN 


Or    1     2     3     4    5 
IdlNUTES  - 


No.  50.— E.  O.  T.,  2d  Lieut. 


PILOT. 


Age  31  years  8  months. 


In  good  health,  but  "  out  of  training  "  and  20  pounds  overweight. 

This  chart  shows  almost  total  failure  to  compensate.  There  is  very  little  change  in 
pulse  or  blood  pressure,  and  the  respiratory  reaction  is  deficient.  For  this  reason  there  is 
early  appearance  of  inefficiency  as  shown  by  the  psychological  characters,  and  he  Is 
"  completely  inefQcient  "  above  9  per  cent.  Since  there  Is  no  circulatory  reaction,  there 
Ui  no  evidence  of  strain.     Class  C.     "  Becomes  inefficient  at  a  relatively  low  altitude." 


AIE    SEBVICE    MEDICAL.  179 

occur,  and  if  present  is  never  very  pronounced,  and  does  not  occur 
before  the  oxygen  is  reduced  to  9.5  per  cent  or  less. 

About  66  per  cent  of  all  men  examined  have  had  a  fall  in  the 
diastolic  pressure.  At  least  half  of  these  have  been  sudden  and  great. 
The  rapid  fall  is  always  associated  with  fainting,  and  usually  precedes 
a  systolic  fall.  If  the  two  occur  together,  in  the  order  just  indicated, 
the  experiment  must  be  terminated  at  once  if  fainting  is  to  be  pre- 
vented. The  pronounced  and  sudden  fall  in*  diastolic  pressure  may 
occur  at  a  high  oxygen  percentage.  It  has  been  found  to  occur  as 
early  as  14  and  13  per  cent  of  oxygen  (10,400  and  12,200  feet).  Such 
sudden  falls  in  the  diastolic  pressure  appear  to  be  due  to  an  over- 
coming of  the  vasomotor  center  by  oxygen  shortage.  A  decided  fall 
in  the  diastolic  pressure  even  if  more  or  less  definitely  controlled  is  an 
indication  that  the  subject  will  not  tolerate  well  the  altitude  corre- 
sponding to  the  oxygen  percentage  at  which  it  appears. 

Three  tj'pes  of  circulatory  reaction  to  oxygen  want  have  been  ob- 
served. The  first,  the  optimum,  in  which  the  pulse  rate  accelerates 
moderately  as  the  oxygeji  decreases,  the  systolic  pressure  is  un- 
changed or  shows  a  terminal  rise  of  not  more  than  20  to  30  mm.  Hg.. 
and  the  diastolic  pressure  remains  unchanged  or  rises  slightly  (see 
chart  2).  The  second,  the  controlled  diastolic  fall,  in  which  the 
pulse  rate  accelerated  moderately  and  the  systolic  pressure  rises 
as  the  diastolic  pressure  gradually  falls  (see  charts  3  and  6).  The 
third,  the  fainting  type  (see  charts  1  and  4),  in  which  after  a  period 
of  fair,  good,  or  excessive  response  in  the  rate  of  heart  beats  to  low 
oxygen  the  diastolic  pressure  suddenly  falls  and  soon  thereafter  the 
systolic  pressure  falls  and  the  pulse  rate  slows.  The  optimum  type 
may  tolerate  as  low  an  oxygen  as  6  per  cent  and  may  lose  con- 
sciousness without  fainting.  He  recovers  quickly  when  restored  to 
air,  while  the  heart  rate  and  blood  pressures  are  soon  back  to  their 
normals.  The  fainting  type  rarely  endures  as  low  an  oxygen  and 
if  allowed  to  run  his  course  faints  completely,  and  as  he  revives  he 
requires  a  considerable  time,  sometimes  an  hour  or  two,  to  regain  his 
normal  pulse  rate  and  blood  pressures.  There  are,  of  course,  grada- 
tions between  the  types  here  described. 

The  pulse  pressure  during  a  rebreathing  test  remains  fairly  con- 
stant in  most  men  until  the  oxygen  has  fallen  to  between  12  and  9 
per  cent  (14,500—22,000  feet),  after  which  it  increases  in  amount 
during  the  further  reduction  in  oxygen.  The  rise  in  pulse  pressure 
occurs  when  the  systolic  pressure  is  rising  and  the  diastolic  either 
remaining  constant  or  slowly  falling.  This  is  also  the  period  when 
the  heart  beat  is  accelerating  most  rapidly.  The  amplitude  of  the 
heart  output,  it  is  claimed,  is  shown  by  the  pulse  pressure;  if  the 

89118—19 13 


180  AIR   SERVICE   MEDICAL. 

pulse  pressure  be  multiplied  by  the  pulse  rate  and  the  product  be 
taken  as  a  relative  measure  of  the  volume  of  the  blood  stream  and 
increase  in  the  circulation  rate  will  be  indicated,  beginning  between 
16  and  14  per  cent  of  oxygen  and  progressively  increasing  as  the 
oxygen  further  decreases.  The  period  of  most  rapid  flow  of  blood 
would,  therefore,  be  that  when  the  pulse  pressure  is  also  increasing, 
that  is,  from  between  12  and  9  per  cent  of  oxygen  to  the  end  of  tho 
test.  Therefore  a  marked  increase  in  the  rate  of  the  circulation  of 
the  blood  during  exposure  to  a  low  and  decreasing  oxygen  is  indi- 
cated. This  increase  in  blood  flow  is,  as  shown  earlier,  an  important 
and  necessary  compensatory  reaction  to  low  oxygen. 

Incidentally  a  few  venous  blood  pressure  determinations  made 
during  exposure  to  a  decreasing  oxygen  supply  have  shown  a  drop 
in  venous  pressure,  which  beconios  very  pronounced  when  the  oxygen 
is  10  per  cent  or  less.    Tho  following  are  typical  examples: 

1.  Normal  venous  blood  pressure  was  10.8  centimeters  of  blood. 
After  25  minutes,  during  which  time  the  oxygen  was  gradually  de- 
creased to  8  per  cent,  it  had  fallen  to  3.5  centimeters  of  blood.  Ke- 
t  urned  to  normal  within  five  minutes  after  being  returned  to  air. 

2.  Normal  venous  j^ressures  9  centimeters;  20  minutes  later  at  10 
per  cent  oxygen,  3.5  centimeters.  Return  to  normal  after  experiment 
required  15  minutes. 

3.  Normal,  6.6  centimeters;  fell  to  5  centimeters  in  30  minutes  when 
I  he  oxygen  had  reached  7.5  per  cent. 

This  fall  in  venous  pressure  calls  to  mind  a  similar  fall  reported 
by  Schneider  and  Sisco  in  men  on  Pike's  Peak,  and  it  indicates  that 
the  reactions  observed  in  the  rebrea thing  tests  are  the  result  of  the 
same  cause — low  oxygen. 

VENOUS   PRESSURK. 

For  the  determination  we  used  a  tilting  table,  which  made  it  easv 
to  stud}'  the  subject  in  the  horizontal  position.  The  subjects  of  our 
studies  were  officers  and  enlisted  men  of  the  laborator}',  presumably 
normal  men. 

Venous  pressure  was  determined  by  noting  the  height  to  which 
the  arm  could  be  lifted  before  some  prominent  bit  of  vein  in  or  near 
the  hollow  of  the  elbow  collapsed,  and  comparing  this  with  the 
height  of  the  point  of  reference  between  these  two  levels,  read  in 
centimeters,  gives  the  venous  pressure  directly  in  centimeters  of 
blood. 

The  point  of  reference  was  taken  as  5  centimeters  below  the  level 
of  the  nipple,  and  this  level  was  carried  away  from  the  breast  by 
means  of  a  simple  spirit  level.  Measurements  were  read  on  a  centi- 
meter rule  suspended  from  the  ceiling. 


AIR   SEBVTOE   MEDICAL. 


181 


•>,)•>>•  Pulse 

Pulse  Pressure 


•  ',  Resp,  in  decih  per  min.     • •  ,Syst.  B.  P 

Accoiii.- In  mm.  Convergence  in  mm. 


n     n    n     o     1     3     3     4     5     6     7     8     8    10    11    12  13   14  15   16   17    18   19  20   2t   23  23  24  25   2C  27   29  •<»   80   31    82   33 

time  in  minutes 

Chabt  4. 


No.  144.— L.  R.  S. 


CADET. 


Age  20  years,  2  months. 


Is  decidedly  "  stale,"  hates  to  go  up  In  the  air  at  all.  Feels  tired  and  depressed,  and 
is  discontented  In  the  service  at  present.  Certain  complications  at  home  are  on  his  mind 
.  good  deal. 

This  chart  Is  typical  of  a  man  in  poor  physical  and  mental  condition.  He  fainted 
rather  suddenly  at  about  13  per  cent.  Previous  to  this  he  had  shown  little  com- 
pensatory response ;  blood  pressure  too  low  from  the  start,  pulse  rising  slightly  and 
respiration  hardly  at  all  affected.  This  man  might  be  expected  to  faint  at  any  time 
during  a  flight.  Irrespective  of  elevation. 

No  rating  given,  but  for  the  time  being  Is  unfit  to  fly  at  all.  Withdrawn  from  flying 
and  recommendation  made  for  furlough. 


182 


AIB  SERVICE   MEDICAL. 


The  data  on  the  venous  pressure  study,  though  meager  as  yet,  are 
sufficient  to  show  that  with  an  increase  of  altitude  there  is  a  decrease 
in  venous  pressure.  This  change  in  venous  pressure  shows  great 
individual  variations,  ranging  from  4.1  per  cent  to  104  per  cent 
drops.  Only  one  case  showed  a  final  rise  in  venous  pressure.  After 
a  drop  from  8.3  centimeters  of  blood  to  5.3  centimeters  of  blood  the 
pressure  started  to  rise  and  continued  to  rise  until  the  end  of  the 
experiment. 

Out  of  nine  cases,  the  one  mentioned  above  was  the  only  one  that 
did  not  show  a  lowered  venous  pressure  under  decreased  oxygen. 
In  many  cases  the  pressure  showed  a  tendency  to  decrease  with  the 
first  indications  of  lowered  oxygen  percentage.  Others  did  not 
respond  until  the  oxygen  had  reached  about  13  per  cent  to  14  per 
cent,  after  which  the  pressure  dropped  quite  abruptly  to  the  end  of 
the  experiment. 

From  eight  cases  studied  with  the  Dreyer  apparatus,  the  following 
data  were  compiled : 


Normal 
V.  P. 

Fall  in 
V.  P. 

Per  cent 
fall. 

o,. 

1                        

Cm.  blood. 
8.75 
6.45 
4.48 
9.70 
2.40 
4.03 
6.30 
6.88 

Cm.  blood. 
9.05 
2.40 

.98 
6.25 
1.10 
2.58 
3.50 

.28 

Per  cent. 
104.0 
37.2 
21.8 
64.5 
45.8 
64.0 
55.5 
4.1 

Percent. 
10.2 

2                                     

7.5 

3.                         

8.5 

4                            

6.6 

5.              

10.0 

6                                     

7.3 

7 

8.7 

8            

8.63 

Average 

6.12 

3.27 

49.6 

8.4"i 

The  above  studies  bear  out  rather  well  the  findings  of  Schneider 
and  Sisco  in  their  Pike's  Peak  investigations,  and  indicate  that  the 
reactions  observed  in  the  rebreathing  tests  are  the  result  of  the  same 
cause — low  oxygen. 


THE  RELAnON  OF  VITAL  CAPACITY,  POWER  TO  HOLD  THE  BREATH  AND 

ENDURANCE  OF  LOW  OXYGEN. 

The  English  suggest  the  rejection  of  all  candidates  with  a  vital 
capacity  below  3,000  cc.  and  view  with  suspicion  all  beloAV  3400  c". 
The  candidate  also  should  be  able  to  hold  the  breath  a  minimum,  in 
three  times,  of  45  seconds.  They  find  that  good  pilots  manage  60 
seconds  or  more.  If  dizziness,  blurred  vision,  etc.,  occur  under  40 
seconds,  they  reject  the  candidate,  no  matter  what  the  vital  capacity 
niay  be.  A  further  test  often  applied  is  to  have  the  candidate  hold 
the  breath  after  the  moderate  exercise  of  stooping  and  touching  the 
floor  four  times.  After  the  exercise  the  candidate  should  be  able  to 
hold  the  breath  30  seconds.    Good  pilots  hold  at  least  40  seconds,  gen- 


AIB   SERVICE   MEDICAL. 


183 


erally  between  50  and  60  seconds.  None  of  the  men  examined  by  us 
had  a  vital  capacity  less  than  3,400  cc.  Four  who  were  unable  to 
endure  a  low  percentage  of  oxygen  in  the  rebreathing  experiments 
had  vital  capacities  ranging  between  4,400  and  5,000  cc.  In  view  of 
our  observations  it  appears  that  the  vital  capacity  does  not  serve  as 
an  index  for  tlie  approximation  of  the  limits  of  endurance  of  low 
oxygen  (see  following  table  prepared  from  observation  on  50  men). 


Vital 
capacity. 

Holding  of  breath. 

Lowest 
per  cent 
of  oxygen 
endured. 

Subject. 

IJefore 
exercise. 

After 
exercise. 

Danger  porcentago. 

An 

4,200 
5,000 
4j600 
3,800 
4,500 
4,350 
4,400 
3,800 
5,200 
4,500 
4,750 
4,700 
3,(«t) 
4.20i0 

Seconds. 
40 
75 
80 
47 

Seconds. 
24 
.W 
58 
38 

Per  cent. 
6.8 
8.4 
9.2 
6.6 
9.S 
7.2 
6.8 
8.8 
6.3 
7.3 
6.3 
6.7 
8.2 
7.3 

Not  reached. 

Br 

10. 

Be 

9.2. 

CI 

8.3. 

Fin 

107  1              34 

11.3. 

Fer 

72 
(iO 

57 
.54 

11.3. 

(iin .          

Not  reachetL 

Kr 

76  1              40 
56                H7 

10. 

Par 

6.3. 

Roc 

62 
75 
60 
62 
29 

30 
74 
24 
32 
20 

10.3. 

Sch .           

7.7. 

Sn  y '. 

8. 

Tr.. 

8.2. 

W 

Not  reached. 

An.,  with  a  vital  capacity  less  than  that  of  Br.,  Be.,  and  Fin.,  had 
not  completely  reached  the  limit  of  endurance  at  6.8  per  cent  (28,400 
feet),  W'hile  Br.  failed  at  8.4  per  cent  (24,000  feet).  Be.  fainted  at 
9.2  per  cent  (21,800  feet),  and  Fin.  at  9.8  (20,000  feet).  Compare 
the  last  three  with  CI.,  whose  vital  capacity  was  only  3,800  cc,  and 
who  endured  low  oxygen  down  to  6.6  per  cent. 

The  length  of  time  the  breath  was  held  did  not  give  an  indication 
of  how  low  in  oxygen  the  subject  would  go  on  the  rebreathing  appa- 
ratus. Fin.  and  Be.,  who  fainted  at  9.8  per  cent  (20,000  feet)  and 
9.2  per  cent  (21,800  feet),  respectively,  held  the  breath  longer  than 
the  average.  An.,  who  managed  only  40  seconds,  withstood  6.8  per 
cent  oxygen  (28,400  feet),  and  W.,  who  held  only  29  seconds,  endured 
low  oxygen  down  to  7.5  per  cent  (26,000  feet). 

VITAL  CAPACITY  AND  INTESTINAL  GASES  AT   HIGH  ALTITUDES. 

That  vital  capacity  of  the  lungs  decreases  with  lowering  atmos- 
pheric pressure  has  long  been  established  by  investigations  carried 
on  in  this  country  and  abroad.  The  cause  of  the  decreased  vital 
capacity  at  high  altitudes  has  not,  however,  been  wholly  determined 
That  oxygen  want  plays  a  part  in  this  as  well  as  in  other  physiologic 
low-pressure  symptoms  seems,  from  our  investigations,  to  be  prac- 
tically certain.  That  oxygen  want  alone  is  not  wholly  responsible 
seems  equally  certain. 


184  AIR   SERVICE   MEDICAL. 

For  our  investigations  we  used  a  simple  water  spirometer  with  a 
capacitj'  of  about  7  liters.  The  work  was  done  in  the  low-pressure 
chamber  under  conditions  simulating  those  encountered  at  altitudes 
ranging  between  sea  level  and  22,000  feet. 

First  a  series  of  observations  was  made  in  which  the  subjects  were 
taken  to  20,000  feet,  without  oxygen,  to  determine  the  amount  of 
decrease  in  vital  capacity.  In  17  cases  the  average  decrease  was 
0.48  liter  (approximately  10  per  cent),  the  maximum  1.08  liters  (25 

Ser  cent),  and  the  minimum  0.15  liter  (3  per  cent).    A  well-defined 
ecrease  does  not  occur  below  10,000  feet;  the  majority  of  men  seem 

to  hold  on  well  to  12,000  to  14,000  feet.  In  this  connection  it  is  inter- 
esting to  note  that  three  men  Avho  have  lived  most  of  their  lives  at 
altitudes  above  5,000  feet  retained  their  normal  vital  capacity  to 
greater  altitudes  than  did  the  men  who  had  always  lived  at  low  alti- 
tudes. In  one  the  first  break  came  at  14,000  feet,  the  second  held  to 
16,000  feet,  and  the  third  was  still  normal  at  18,000  feet.  On  the 
other  hand,  several  whose  homes  had  been  at  less  than  1.000  feet 
showed  a  decreased  capacity  at  10,000  feet. 

A  second  series  was  run  in  which  the  subjects  took  oxygen  through- 
out the  experiment,  and  in  this  series  there  also  occurred  a  decrease 
in  vital  capacity.  In  six  cases,  going  from  sea  level  to  20,000  feet, 
the  average  decrease  in  vital  capacity  was  0.20  liter,  or  4.5  per  cent 
below  normal. 

A  number  of  men  were  taken  to  20,000  feet  without  oxygen.  At 
that  altitude  they  were  given  oxygen  and  held  a  sufficient  length  of 
time  for  the  oxygen  to  effect  the  system.  The  usual  decrease  to  20,000 
without  oxj^gen  was  observed.  When  oxygen  was  administered  a 
definite  and  unmistakable  return  toward  the  normal  was  noted,  but 
in  no  case  did  the  readings  at  20,000  feet  equal  the  normal  readings 
at  sea  level.    In  a  study  of  six  cases  the  following  data  were  obtained : 

Average  V.  C.  at  sea  level 4.4.5 

Average  V.  C.  at  20,000  feet  without  Oj 3.94 

Average  V.  C.  at  20,000  feet  after  taking  0-, 4.23 

That  the  aviator  rasij  be  distressed  by  an  abdominal  bloating  due 
to  expansion  of  gases  in  the  intestine  during  an  ascent  has  been  sug- 
gested. The  gases  accumulated  in  the  digestive  organs  expand  as 
the  external  pressure  falls  so  that  at  18,000  feet — that  is,  half  an 
atmosphere  of  pressure — the  gases  in  the  digestive  organs  will  expand 
to  double  their  volume.  This  may  lead  to  an  unpleasant  pressure  on 
the  abdominal  wall  and  diaphragm  and  this,  it  has  been  suggested, 
might  cause  difficulty  in  breathing  hj  forcing  up  the  diaphragm  and 
thus  decreasing  the  space  of  the  thoracic  cavity.  When  gas  forms 
continually  in  the  digestive  organs  in  consequence  of  a  diet  rich  in 
carbohydrate  foods,  such  as  sugars,  green  vegetables,  and  others  that 
are  easily  fermented,  the  decrease  in  vital  capacity  might  be  expected 


AIB    SEBVICE    MEDICAL. 


185 


o  T  ^  ._.>...  ResD.  in  decil.  per  min.     •....♦•••••Syst.  B.  P 


No.  352.— R.  P.  E. 


Age  22  years,  7  months. 


Preliminary  blood  pressures:  Reclining,  134;  standing,  142;  after  exercise,  160;  two 

mlnntes  later,  134.  .  ,.  ■n^■.„„^.^^^„ 

During  the  test  has  a  high  and  gradually  increasing  systoUc  pressure.  Diastolic 
comes  down  rather  steeply  after  20  miuuteB  (10  per  cent),  though  never  out  of  control. 
Pulse  and  respiration  normal.  Marked  psychic  effects  soon  after  diastolic  pressure  be- 
gins to  fall  High  blood  pressure,  with  signs  of  fatigue,  but  candidate  in  class  C  In 
spite  of  bis  reaching  a  fairly  low  percentage  before  the  actual  break. 


186  AIR  SERVICE   MEDICAL. 

to  be  greater  than  in  the  man  in  whom  little  or  no  fermentation  is 
occurring.  Careful  study  of  this  condition  failed  to  establish  any 
relation  between  abdominal  blpating  and  the  decrease  in  vital 
capacity  during  experiments  in  the  low-pressure  chamber.  It  was 
found  that  the  abdominal  measurements  may  vary  greatly  at  any 
single  pressure  while  the  vital  capacity  remains  constant.  Belching 
or  otherwise  releasing  the  digestive  gases  reduced  the  abdominal 
measurements  and  materially  relieved  the  distress  of  the  subject 
witliout  causing  any  noticeable  change  in  the  vital  capacity. 

The  decrease  in  vital  capacity  of  the  lungs  appears,  therefore,  to  b? 
largely  due  to  the  oxygen  want  of  high  altitudes  and  not  to  be  caused 
by  the  pushing  up  of  the  diaphragm  by  the  expanding  gases  of  the 
intestines. 

VASOMOTOR  TONE  AND  ENDURANCE  OF  LOW  OXYGEN. 

Since  ph37sical  fitness  has  been  found  to  influence  profoundly  the 
abilit_y  of  men  to  endure  low  oxygen  it  was  tliought  that  Crampton's 
"blood  ptosis  test"  might  be  used  to  approximate  the  altitude  the 
aviator  could  tolerate.  The  vasomotor  mechanism  is  easily  wearied 
and  damaged  by  unhygienic  influences.  The  fact  that  the  vasomotor 
control  of  the  splanchnic  area  in  man  experiences  a  change  of  adjust- 
ment when  the  body  is  moved  from  the  horizontal  to  the  upright- 
standing  position  has  been  used  by  Crampton  to  devise  a  percentage 
scale  of  vasomotor  tone  for  rating.  In  vigorous  subjects  the  heart 
rate  does  not  increase  on  standing  but  in  wearied  subjects  it  increases 
as  much  as  44  beats  per  minute.  In  a  perfectly  strong  subject  the 
splanchnic  vasotone  will  increase  on  standing  and  raise  the  systolic 
blood  pressure  about  10  millimeters  of  Hg.  while  in  an  individual 
weakened  by  dissipation,  overwork,  or  lack  of  sleep  the  pressure  will 
tend  not  to  rise  but  to  fall.  To  estimate  the  vasomotor  tone  the  pulse 
rate  and  the  systolic  pressure  are  determined  on  a  subject  after  re- 
clining five  minutes  and  again  after  he  is  required  to  stand.  A  sub- 
ject sometimes  may  show  weakness  by  a  decrease  in  blood  pressure 
and  at  other  times  by  an  increase  in  heart  rate,  and  vice  versa.  It 
was  determined  that  a  decrease  of  one  millimeter  of  mercury  was 
equivalent  to  an  increase  in  heart  rate  of  approximately  two  beats. 

A  study  of  130  aviators  .in  which  the  vasomotor  tone  index  was 
compared  with  the  physiological  compensatory  reactions  during  ex- 
posure to  the  influence  of  the  low  oxygen  of  the  rebreathing  test  has 
shown  that  Crampton's  vasomotor  tone  index  does  not  give  a  reliable 
indication  of  the  subject's  ability  to  withstand  low  oxygen  tensions. 
When  the  candidates  are  arranged  in  the  four  groups  of  our  scheme 
for  classifying  aviators  the  AA  group  has  an  average  vasomotor  tone 
of  88.75,  the  A's  68.25,  the  B's  57,  niid  the  C's  68.13.  Collectively, 
therefore,  the  vasomotor  tone  index  appears  to  furnish  information 


AIB   SERVICE   MEDICAL. 


187 


Legend 


-•Diast.  B.  P. 


«w<i»»«i<«PuIse  •- 

Pulse  Pressure 


-•Resp.  in  decil.  per  min. 
Accom.  in  mm. 


« «Syst.  B.  P 

Convergence  in  mm. 


BSjjgigiiii^gii^^ 


n     tj     n     0      1      2 
TIMK  FN*  MINUTES 

No.  351  .—W.  S. 


4     5     6 


9     10    n    12    13    14   1.5    10    IT    IS    19    20    ^I    2i    il   il@5   20   27   2S  29    .30   SI    82   S3 


Chabt  6. 


Age  20  years  4  months. 


Preliminary  blood  pressures :  Reclining,  122 ;  standing,  138 ;  after  exercise,  156,  and 
two  minutes  later,  138. 

During  the  test  the  pressure  is  a  little  high  and  trends  upward.  The  diastolic  pressure 
begins  to  fall  rather  rapidly  after  the  nineteenth  minute  (10.5  per  cent),  but  is  never 
out  of  control.  At  the  same  time  systolic  pressure  falls  somewhat  and  the  pulse  fails 
to  advance.  This  is  the  picture  of  circulatory  fatigue,  and  if  pushed  much  longer  col- 
lapse would  follow.  Note  that  marked  psychological  effects  (diamonds)  appear  just  as 
the  circulatory  fatigue  becomes  manifest.  Complete  inefficiency  at  a  rather  high  per- 
centage (8  per  cent).     (Tlass  B. 


188  AIR   SERVICE   MEDICAL. 

that  might  be  useful  except  for  the  C  group.  The  number  of  men 
in  class  C  is  rather  small,  5  in  all,  so  that  the  chance  for  error  is 
greater.  An  examination  of  the  individual  cases  in  the  four  groups 
shows  clearly  that  the  Crampton  vasomotor  tone  index  can  not  be 
depended  upon  as  a  test  for  ability  to  react  to  low  oxygen.  Thus 
among  the  A's  are  vasomotor  tones  as  low  as  30  and  as  high  as  110, 
among  the  B's  15  and  105.  With  such  a  wide  range  of  variation  it 
becomes  evident  that  the  vasomotor  tone  index  can  not  be  substituted 
for  the  rebreathing  test.  Low  vasomotor  tone  is  no  doubt  present  in 
physically  stale  men,  but  it  also  occurs  in  men  temporarily  fatigued. 

THE  PULSE  RATE  AND  BLOOD  PKESSURES   AFTER  PHYSICAL   EXERTION. 

It  is  generally  assumed  that  in  vigorous  physically  fit  men  the  rate 
of  heart  beat  does  not  accelerate  as  much  during  a  given  exercise  as 
in  men  out  of  training  and  therefore  physically  "  soft."  Further- 
more, in  the  physically  fit  the  rate  returns  to  normal  quickly,  while 
in  the  less  strong  a  higher  rate  is  maintained  some  time  after  exer- 
cising. After  short  periods  of  exertion  the  pulse  rate  usually  goes 
subnormal,  but  after  fatiguing  and  exhausting  exercise  returns  to 
normal  more  slowly  and  only  rarely  passes  into  the  subnormal  stage. 
The  amount  of  increase  in  the  heart  rate  and  the  time  required  to 
return  to  normal  may  be  used  as  a  measure  of  physical  fitness. 

All  aviators  and  candidates  examined  in  the  Medical  Research 
Laboratories  undergo  the  following  test:  The  candidate  stands  at 
ease  while  his  pulse  rate  is  counted;  when  two  successive  counts  are 
the  same  the  rate  is  recorded,  and  the  arterial  blood  pressures 
immediately  taken.  The  candidate  then  places  his  right  foot  on  a 
chair  and  raises  himself  five  times  to  the  erect  position  on  the  chair. 
This  exercise  requires  about  15  seconds.  Immediately  thereafter  the 
pulse  rate  is  counted  for  20  seconds,  and  next,  as  quickly  as  possible, 
the  arterial  pressures  are  determined.  He  then  stands  at  ease  for 
two  minutes,  after  which  the  pulse  rate  and  pressures  are  again 
taken. 

An  analysis  of  ITO  cases  t^ken  at  random  has  been  made  and  com- 
parisons made  with  the  reaction  of  the  candidate  to  the  low  oxygen  of 
the  rebreathing  test.  Also  a  comparison  with  the  vasomotor  tone  has 
been  made.  The  following  changes  in  pulse  rate  were  obtained 
immediately  after  the  exercise :  Decrease  in  7.1  per  cent,  no  change  in 
7.6  per  cent,  an  increase  of  from  1  to  10  beats  in  38.2  per  cent,  an 
increase  of  from  11  to  20  in  34.1  per  cent,  and  21  to  30  in  13  per  cent. 
Just  what  increase  in  the  rate  of  heart  beat  is  excessive  is  yet  to  be 
determined.  Maj.  Flack  and  Capt.  Bowdler  conclude  for  the  same 
exercise  that  an  increased  rate  of  over  25  and  a  return  period  of  over 
30  seconds  are  points  calling  for  careful  consideration.     Only  6.5 


AIB   SEBVICE   MEDICAL.  189 

per  cent  of  our  subjects  had  an  increase  of  over  25  beats.  On  com- 
paring the  above  data  with  the  showing  the  men  made  in  ability  to 
compensate  to  the  low  oxygen  of  the  rebreathing  test,  we  find  no 
definite  relationship  indicated  between  the  amount  of  acceleration 
after  exercise  and  endurance  of  low  oxygen.  Neither  do  we  finrl  :i 
relationship  between  the  exertion  pulse  rate  acceleration  and  Cramp 
ton's  vasomotor  tone  index. 

We  did  not  follow  the  return  of  the  pulse  rate  to  normal  after  ex- 
ercise but  noted  the  rate  two  minutes  after.  The  rate  at  the  end  of 
the  second  miiiute  was  above  normal  in  33  per  cent,  normal  in  16.8 
per  cent,  and  sul^normal  in  50.2  per  cent  of  the  men.  None  of  the 
subjects  had  a  rate  of  over  10  above  normal  at  the  end  of  two  minutes. 
The  number  above  normal  is  certainly  excessive  according  to  the 
standards  of  Flack  and  Bowdler.  In  this  study  no  relationship  could 
be  established  with  the  ability  to  compensate  to  low  oxygen  nor  v^^itli 
the  vasomotor  tone. 

The  changes  in  the  systolic  pressure  immediately  after  the  exercise 
show  nothing  definite  as  to  physical  condition  and  as  to  abilitj?^  to 
endure  low  oxygen.  The  systolic  pressure  two  minutes  after  exercise, 
when  compared  Avith  the  pulse  rate  changes,  show  collectively  inter- 
esting differences.  The  group  with  the  pulse  rate  above  nomial  had 
systolic  pressures  above  normal  in  22.8  per  cent  and  below  normal 
in  66  per  cent  of  the  men;  those  whose  pulse  rate  had  returned  <o 
normal  showed  68  per  cent  above  and  18  per  cent  below  the  normal 
systolic  pressure:  Avhile  in  those  in  which  the  pulse  rate  was  sub- 
normal 82.1  per  cent  were  above  and  only  7.1  per  cent  below  their 
normal  systolic  pressure.  It  appears,  therefore,  that  when  the  heart 
rate  remains  up  after  exercise  the  systolic  pressure  more  frequently 
becomes  subnormal.  This  observation  has  not  been  found  to  bear 
upon  the  abilitj'^  of  men  to  react  to  low  oxygen.  It  does,  however, 
indicate  that  the  vasomotor  tone  index  is  a  more  reliable  method  of 
judging  fatigue  and  possibly  staleness  than  either  a  study  of  the 
pulse  rate  or  systolic  pressure  alone. 

Flack  and  Bowdler  believe  the  ideal  pulse  rate  for  a  flying  officer 
has  a  small  range  between  systolic  and  diastolic  pressures  (20-30) 
with  a  rest  rate  increased  20-25  by  exercise  and  returning  to  the 
rest  rate  in  10-15  seconds.  They  further  state  that  a  pulse  of  60  to 
72  little  raised  by  exercise  (10  beats  per  minute)  and  returning  to 
normal  in  10  seconds  is  a  good  sign,  generally  associated  with  excel- 
lent physique  and  good  stability  of  the  nervous  system.  We  have  no 
reason  to  doubt  their  conclusion  but  believe  the  values  given  maj' 
be  increased  by  a  good  margin  and  still  retain  the  physical  perfection 
desired.  About  37  per  cent  of  our  subjects  had  when  standing  up- 
right pulse  rates  above  85  and  the  pulse  pressures  of  the  great  ma- 


190 


AIR   SERVICE    MEDICAL. 


Legend       ,.—  — j!,0.%.  •  h  it  t  •  Pulse  ^ 

•— «••  Diast  B.  P. 


Pulse  Pressure 


Resp.' in  decil.' per  min.         ,  • •Syst.  B.  P 

Convergence  in  mm. 


Accom.  in  mm. ' 


n.   n    n     o     1      2     3      4     5      6      7      8     9    10    11    12   13    14   15    18    17    13  ,19   30    21   82   33    24   20   26   27   28   28    30    31    S2    ^ 

time  in  minutes  €7  '  ^ 

Chabt  7. 


No.  154.— S.  A.  C. 


CADET. 


Age  23  years  5  months. 


Good  condition. 

This  chart  Is  rather  a  curiosity.  It  shows  (aside  from  a  psychic  rise  at  the  start) 
practically  no  low  oxygen  effect  on  pnlse  or  blood  pressure.  There  is  fair  response  in 
respiration.  In  spite  of  this,  the  subject  preserves  his  eflBciency  by  the  psychological 
tests  to  a  very  low  percentage,  viz,  6.8  per  cent.  This  is  a  most  unusual  case,  which 
should  be  investigated  further.  There  is  no  doubt  that  he  compensates  in  some  way, 
Bioce  his  efficiency  holds  out  so  well,  but  he  does  not  do  it  in  the  usual  way.  Most 
ca^es  showing  such  lack  of  response  in  poise  would  show  early  inefficiency.     Bated  AA. 


AIB   SERVICE    MEDICAL.  191 

jority  ranged  between  30  and  60  nini.  Hg.  They  believe  that  a 
diastolic  pressure  below  70  with  a  pulse  pressure  greater  than  50, 
is  strong  evidence  that  the  cardiovascular  system  is  unsuited  for 
air  work.  About  30  per  cent  of  our  fliers  have  had  when  standing 
a  pulse  pressure  greater  than  50.  The  method  of  taking  the  arterial 
pressures  may  account  for  the  differences  noted.  We  have  used  the 
Tycos  sphygmomanometer  and  taken  the  pressures  with  the  arm  at 
th^  side  by  the  auscultatory  method,  the  systolic  pressure  being  read 
at  the  point  of  reappearance  of  the  pulse  and  the  diastolic  pressure 
at  the  point  of  disappearance  of  the  sound. 

In  comparing  our  data  with  the  conclusions  of  Flack  and  Bowdler 
we  find  33  per  cent  of  our  men  had  a  pulse  rate  above  normal  at  the 
end  of  two  minutes.  Without  taking  into  consideration  the  inter- 
play between  pulse  rate  and  systolic  pressure,  it  apparentlj'^  would 
not  be  just  to  rule  against  the  subject  because  of  a  slow  return. 

OBSERVATIONS   ON   THE  EFFECTS  OF   FLYING   UPON   THE   PULSE   RATE   AND 

TirE  ARTERIAL  PRESSURES. 

The  experiments  were  carried  out  on  the  flying  plateau  immedi- 
ately before  and  after  a  flight.  The  aviator  reclined  for  five  minutes, 
after  which  the  pulse  rate  was  counted  and  the  pressures  then  taken. 
He  next  was  required  to  stand  while  each  Avas  again  determined.  The 
same  method  of  examination  was  followed  before  and  after  flight. 
Such  observations  are  still  being  continued.  None  of  the  flights  have 
exceeded  a  height  of  more  than  6,000  feet,  while  the  average  altitude 
attained  varied  between  2,500  and  4,000  feet.  The  duration  of  the 
flight  rarely  exceeded  an  hour.  The  pulse  rate  in  both  postures  was 
foimd  to  be  more  rapid  after  than  before  the  flight  in  about  60  per 
cent  of  the  men,  was  unchanged  in  20  per  cent,  and  was  decreased 
in  20  per  cent.  The  increase  was  in  several  as  high  as  28  beats  pei" 
minute.  The  excitement  attending  the  anticipation  of  the  flight  was 
evidenced  in  a  more  rapid  pulse  rate  only  in  men  who  had  but  little 
experience  in  solo  flying  or  had  some  trouble  in  previous  flying. 

The  systolic  pressure  in  both  postures,  reclining  and  standing,  was 
higher  after  than  before  the  flight  in  approximately  75  per  cent  of 
the  men  studied,  20  per  cent  had  a  lower  systolic  pressure  on  the  re- 
turn, while  about  5  per  cent  showed  no  change.  The  amount  of  rise 
above  normal  ranged  from  2  to  34  millimeters  of  mercuiy.  The 
greatest  fall  was  10  millimeters  of  mercury. 

The  diastolic  pressure  was  in  approximately  56  per  cent  of  the  men 
lower  after  flying  than  before.     In  no  case  was  the  fall  excessive. 

By  balancing  the  systolic  pressure  and  the  heart  rate  for  reclining 
and  standing  postures  to  determine  the  efficiency  of  the  vasomotor 
system  and  rating  the  reaction,  according  to  Crampton's  scale  of 
vasomotor  tone,  we  find  that  the  majority  of  the  aviators  studied  show 


192 


AIR  SERVICE   MEDICAL. 


Legencl 


0.%    ,  •.mm. 

Diast.  B.  P. 


Pulse  — — — ^ -Resp.  in  <leclf.  per  min.     • '.  •  •    Syst.  B.  P 

Pulse  Pressure  Accom.  in  mm.  Convergence  in  mm. 


A     n    -no     13     3 

TIME  IK  MINUTES 


No.  110.— R.  S. 


as   20    30    3t    3i    •6'i 


Chabt  8. 

CADET. 


Age  .3.5  years  11  months. 


This  chart  is  of  a  type  which  Is  not  uncommon  among  older  subjects,  and  must  be 
interpreted  either  as  decreased  flexibility  of  the  arteries  or  less  effective  vasomotor 
control.  If  emphasizes  the  fact  shown  by  experience  that  the  best  age  for  flying  is  the 
early  twenties — a  man  of  36  has  already  begun  to  grow  old. 

Preliminary  blood  pressures  :  Reclining,  124 ;  standing,  132 ;  after  exercise,  142 ;  and 
two  minutes  later,  124. 

During  the  test  the  systolic  pressure  rises  at  the  start  and  remains  at  about  160. 
As  often  happens  when  systolic  is  high,  there  is  not  a  very  marked  rise  in  pulse.  There 
is  no  evidence  of  circulatory  fatigue,  and  he  reaches  a  low  oxygen  percentage  with 
excellent  command  of  his  faculties.  His  present  performance  is  first  class,  but  it  Is 
unlikely  that  he  would  remain  in  condition  long  if  he  runs  such  a  blood  pressure  when 
he  flies.     Class  B. 


AJR  SERVICE   MEDICAL.  193 

evidence  of  circulatory  fatigue  after  the  flight.  The  vasomotor  tone 
fell  in  at  least  65  per  cent  of  the  men ;  in  some  the  fall  was  slight,  but 
in  several  instances  it  exceeded  30  per  cent.  In  view  of  the  limited 
amount  of  field  study  of  the  aviator  and  the  fact  that  the  flying  has 
been  at  comparatively  low  altitudes,  final  conclusions  can  not  yet  be 
made.  From  the  data  available  it  appears  that  low  flying  fatigues 
the  circulatory  mechanism,  but  not.  however,  as  much  as  the  same 
time  spent  in  physical  work. 

THE  HEMOGLOBIN   WHEN   UNDER  A  DECREASING  OXYGEN  SUPPLY. 

Since  an  increase  in  the  perceutage  of  hemoglobin  in  the  blood  is 
one  of  the  most  important  of  the  low  oxygen  compensations  found 
to  occur  in  men  and  animals  living  at  high  altitudes  on  mountains, 
it  is  interesting  to  find  that  it  may  also  occur  during  short  exposure 
to  low  oxygen.  The  rebreathing  test  of  not  more  than  30  minutes 
duration  is  too  short  a  period  of  time  to  permit  a  concentration  of 
hemoglobin  in  the  majority  of  men.  Only  an  occasional  subject  may 
show  a  definite  concentration.  In  order  to  test  out  the  part  that  the 
blood  changes  may  play  as  a  compensatory  factor  for  oxygen  want 
in  such  a  short  period  as  the  aviator  spends  in  the  air,  a  series  of  ex- 
periments are  now  being  made  in  the  pneumatic  or  low  pressure 
chamber  and  also  under  low  oxygen.  In  these  the  subject  is  held  at 
a  chosen  pressure  or  a  given  percentage  of  oxygen  for  from  40  to  90 
minutes,  the  entire  experiment  lasting  as  much  as  two  or  two  and  a 
half  hours.  The  hemoglobin  has  been  determined  by  two  methods, 
the  Gower-Haldane  heraoglobinometer  and  the  Du  Bousque  (colorime- 
ter, on  blood  taken  from  a  finger  or  an  ear,  and  also  from  a  vein  in 
the  arm. 

At  least  25  per  cent  of  all  men  examined  have  shown  a  well-de- 
fined increase  in  the  percentage  of  hemoglobin,  and  the  majority  some 
evidence  of  concentration.  We  have  found  that  the  blood  from  the 
finger  or  ear  and  from  the  Aein  showed  it  equally  well  by  the  two 
methods  used  in  the  determinations.  The  following  illustrates  the 
amount  of  concentration:  Normal  per  cent  of  hemoglobin  with  the 
Gower-Haldane  hemoglobinometer,  from  a  finger  100,  from  a  vein  90. 
After  80  minutes  under  low  oxygen,  60  of  which  were  spent  at  10  per 
cent  oxygen,  finger  105,  vein  102.  The  amount  of  concentration  has 
been  as  great  as  9.5  per  cent.  It  has  been  most  clearly  induced  at 
pressures,  and  percentages  of  oxygen,  corresponding  to  between 
18,000  and  20.000  feet.  Almost  all  of  the  men  have  had  to  be  held  at 
the  high  altitudes  20  or  more  minutes  before  concentration  began  to 
be  evident. 

Since  the  blood  changes  do  not  always  occur,  and  are  slow  in  ap- 
pearing when  they  do,  the  determination  of  hemoglobin  during  a  re- 
breathing  test  has  not  been  made  a  part  of  the  routine  examination. 


194 


AIB  SEBVICE  MEDICAL. 


Legend 


■    '    ■  '   0.%  •illli*iutt*      Pulse      ■•  —  - 

■•— •  Diast.  B.  P.  Pulse  Pressure 


■  ■  Reap,  in  decil.  per  min.    *.-...»  ....^yst.  B.  P 
Accom.  in  mm.  Convergence  in'.inm. 


finn012     345S7 
TiME  IK  MINUTES 


»  10  11  12  18  14  15  1«  17  18  19  30  21  22  23  24  25  20  27  2S  29  30  31  82  83 

Chabt  9. 


AIR  SERVICE   MEDICAL. 


195 


■0.,%  •iiiii«iiiii»um.    Pulse  « _,Resp.  in  cfecil.  per  min.     ♦..,...,.#  Syst.  B,  P 

,Diast..B.  P.  Pulse  Pressure  Accoin.  in  mr)i.  Convergence  in  mm. 


f^O., 


j\-   n,  n     0      X      a     n      4     5     f>      ;     8     9     10    J)    12    13    M    15    J'i    17    i;i    1.0   211    il    2^   2;J    ;.'J    ii   2(1  i:   2S   '.Ja^iO   aj    32   83 

Chakt  10. 
No.  63. — J.  E.  S.  CADET.  Age  21  years  1  month. 

Left  hospital  tliree  days  ago,  wtiere  he  was  laid  up  for  a  week  with  influenza.  Feeling 
fairly  well  to-day,  though  not  up  to  his  usual  form. 

The  first  chart  is  typical  of  a  man  out  of  condition,  rather  high  systolic  pressure, 
psycl^ic  ri.se  in  both  pulse  and  pressure,  followed  by  a  sudden  faint  at  about  8  per  cent. 
In  this  the  diastolic  pressure  fell  practically  lo  zero;  the  systolic  pressure  and  pulse 
also  broke  sharply,  as  may  be  seen  by  the  .slow  recovery  after  the  experiment  was 
terminated. 

He  was  tested  again  two  weeks  later  (chart  not  given),  and  made  a  very  good  run, 
with  the  exception  of  a  rather  high  blood  pressure  (148.1.  Ip  this  test  he  was  not 
completely  inefficient  when  taken  off  at  5.5  pi^r  cent.  After  two  weeks  he  was  given  a 
third  test  (second  chart),  which  entitles  him  to  an  AA  rating.  The  systolic  pressure 
stays  below  140,  there  is  no  break  in  diastolic,  and  there  ia  a  moderate,  healthy  rlije 
in  pulse. 

This  case  illustrates  the  very  serious  effects  of  temporary  Indisposition. 

89118—19 14 


196       ,  ATE  SEEVIOE  MEDICAL. 

THE    RELATIVE    VALUE   OF   THE    COMPENSATORY    FACTORS. 

In  order  that  a  better  understanding  might  be  had  of  the  inter- 
play of  the  compensatory  factors,  when  man  ascends  quickly  to  very 
high  altitudes  and  remains  only  a  short  time,  a  few  hours  at  the 
most,  a  number  of  experiments  have  been  made  with  men  in  the 
pneumatic  chamber  and  also  under  low  oxygen  in  which  they  have 
been  held  for  an  hour  or  two  under  conditions  corresponding  to 
altitudes  of  15.000  to  20,000  feet.  In  all  of  these,  two  of  the  compen- 
satory changes,  those  in  breathing  and  in  circulation,  have  appeared 
almost  simultaneously  and  increased  steadily  with  the  gradually  in- 
creasing altitude.  When  the  desired  altitude  was  reached  and  then 
maintained  the  breathing  either  continued  at  the  depth  it  had 
acquired  during  the  period  of  progressive  change  or  it  became  still 
deeper  for  a  time.  The  pulse  rate,  which  gives  an  index  of  the  in- 
crease in  the  rate  of  blood  flow,  accelerated  during  the  period  corre- 
sponding to  ascent;  and,  then,  when  the  altitude  was  held,  usually 
remained  constant,  or,  in  some  of  the  men,  retarded  somewhat  after 
the  hold  began.  A  slowing  of  the  pulse  rate,  when  an  altitude  was 
maintained  for  a  time,  was  so  frequently  observed  that  we  sought  for 
an  explanation  of  the  decrease  in  rate.  In  a  number  of  men  it  was 
found  that  the  heart  was  being  relieved  by  other  compensatory 
factors.  In  such  cases  one  or  the  other  or  both  of  two  changes 
occurred.  There  occurred  either  a  further  deepening  of  the  breath- 
ing, or  a  concentration  of  the  hemoglobin,  or  both  of  these  changes 
took  place  together.  Often  the  breathing,  after  increasing  in  amount 
during  the  ascent,  held  at  a  constant  increased  depth  during  the  stay 
at  the  given  altitude;  but  in  such  the  hemoglobin  was  found  to  be 
concentrating  as  the  pulse  rate  slowed. 

An  unusual  but  interesting  case  was  found  in  a  man  whose  breath- 
ing failed  to  respond  to  the  changes  in  altitude.  He  did  not  tolerate 
the  low  pressure  well  at  first,  but  felt  better  after  some  time  had 
been  spent  at  the  chosen  pressure.  In  this  man  the  heart  accelerated 
decidedly  and  later  his  hemoglobin  concentrated  about  8  per  cent. 
His  improvement  occurred  when  the  hemoglobin  showed  concen- 
tration. 

As  yet  no  attempt  has  been  made  to  study  oxygen  secretion  during 
our  rebreathing  experiments  or  in  the  pneumatic  chamber. 

Our  studies  show  that  during  short  exposures  to  high  altitudes,  or 
low  oxygen,  such  as  the  aviator  experiences,  the  compensatory  re- 
actions of  the  body  to  a  decreased  oxygen  are  made  almost  entirely 
by  the  circulation  and  by  the  breathing.  A  few  men  may,  after  the 
lapse  of  an  hour  or  more,  secure  some  benefit  from  a  slowly  develop- 
ing concentration  of  the  hemoglobin  of  the  blood.  The  order  of  re- 
sponse by  the  adaptive  mechanisms  is  not  that  of  the  good  reaction 


ATB  SEEVIOE  MEDICAL.  197 

seen  among  mountaineers,  in  whom  the  breathing  first  responds  while 
the  other  compensatory  changes  take  place  more  slowly.  The  reaction 
resembles  more  nearly  that  seen  during  an  attack  of  mountain  sick- 
ness among  mountaineers.  In  such  men  the  heart  beat  is  greatly  ac- 
celerated during  the  attack.  The  aviator,  it  appears,  must  depend 
largely  upon  his  heart  and  his  breathing  for  compensation  to  the 
fall  in  oxygen  which  he  encounters  as  he  ascends. 

The  length  of  time  taken  to  reach  a  low  oxygen  in  the  rebreathing 
test  will  profoundly  alter  the  ability  to  endure  extremely  low  per- 
centages. If  the  oxygen  is  lowered  rapidly,  the  candidate  compen- 
sates to  a  lower  percentage  than  is  possible  where  the  rate  of  decrease 
in  the  oxygen  is  slower.  Three  rebreathing  experiments  made  on  the 
same  subject  illustrate  the  condition.  The  volume  of  air  was  so  small 
for  the  first  test  that  in  23^  minutes  the  oxygen  was  lowered  to  6.3 
per  cent,  at  which  the  subject's  power  of  compensation  failed.  The 
next  day,  rebreathing  a  larger  volume  of  air  for  38  minutes,  he  com- 
pensated to  7  per  cent  only.  On  the  following  day,  in  a  test  of  85 
minutes'  duration,  compensation  failed  at  8.7  per  cent  of  oxygen. 
Individual  differences  will  be  found;  in  some  men  time  has  a  more 
profound  influence  than  in  others.  Thus,  another  subject  compen- 
sated in  a  test  of  36  minutes  down  to  7.5  per  cent  and  in  one  of  90 
minutes  to  8  per  cent  of  oxygen.  Therefore,  when  testing  ability  to 
endure  low  oxygen,  some  allowance  must  be  made  for  the  time  taken 
to  reach  a  given  percentage.  If  each  of  two  men  tolerate  down  to  7 
per  cent  oxygen  but  one  is  carried  down  in  20  and  the  other  in  40 
minutes,  the  one  who  endures  for  40  minutes  will  have  the  better 
power  of  compensation. 

Control  tests  have  been  conducted  in  the  pneumatic  or  low-pressure 
chamber  to  determine  the  reliability  of  the  rebreathing  test.  A  sub- 
ject was  first  under  observation  in  a  rebreathing  test,  and  on  the  fol- 
lowing day  taken  into  the  low-pressure  chamber  for  similar  observa- 
tions, while  the  pressure  was  lowered  at  the  same  rate  that  the  oxygen 
had  been  absorbed  in  the  rebreathing  test.  The  breathing,  pulse  rate, 
and  blood  pressures  reacted  about  the  same  in  each  experiment.  In 
order  that  a  comparison  might  be  made  of  the  breathing  under  the 
two  conditions  the  alveolar  air  was  analyzed  from  time  to  time  dur- 
ing each  kind  of  test.  A  fall  in  the  alveolar  carbon  dioxide  and 
oxygen  pressure  occurred  in  both  experiences.  The  average  amount 
of  fall  for  eight  men  at  the  per  cent  of  oxygen  or  pressure  corre- 
sponding to  20,000  feet  was  for  carbon  dioxide  during  rebreathing 
8.5  millimeters  and  low  pressure  9.3  millimeters;  for  the  oxygen  in 
rebreathing  66,2  millimeters  and  low  pressure  68.8  millimeters. 
These  figures  show  that  the  increase  in  the  breathing  and  lung  venti- 
lation was  about  the  same  under  the  two  different  low-oxygen  experi- 
ences.   The  pulse  rate  also  was  found  to  begin  to  accelerate  at  about 


198  AIR   SERVICE   MEDICAL. 

the  same  time  in  each  Irind  of  test  and  to  accelerate  in  equal  degree. 
Those  and  other  physiological  observations  made  on  men  undergoing 
the  rebreathing  test  or  under  decreasing  atmospheric  pressure  prove 
that  the  same  compensations  are  used  by  the  body  in  each,  and  those 
we  laiow  are  the  adjustments  made  to  the  influence  of  oxygen  want. 

ALVEOLAR  AIR   PRESSURES   IN   THE  LOW   PRESSURE   CHAMBER   AND   ON    THE 

REBREATHING  APPARATUS. 

Whether  the  individual  is  in  the  low-pressure  chamber  or  on  the 
rebreathing  apparatus  he  can  equally  well  be  subjected  to  gradually 
decreasing  oxygen  pressure.  The  rebreathing  machine  has  been 
shown  to  be  equivalent  to  the  low-pressure  chamber  for  testing  the 
ability  of  an  individual  to  adapt  himself  to  low  oxygen  pressure  so 
far  as  circulatory  and  psychological  reactions  are  concerned.  A  con- 
sideration of  the  respiratory  factors  in  each  was  necessary  in  order  to 
complete  the  comparison.  The  respiratory  factors  to  be  considered 
are:  First,  the  alveolar  air  pressures;  second,  the  volume  per  minute 
and  rate ;  third,  the  blood  gases. 

A  series  of  experiments  were  carried  out  to  show  the  changes  in  the 
alveolar  air  pressures  during  an  ordinary  rebreathing  test  lasting 
about  30  minutes,  in  which  the  subject  was  exposed  to  a  fall  of  oxygen 
per  cent  from  20.96  to  9.8,  or  corresponding  barometric  pressures  of 
760  mm.  to  350  mm,  (20,000  feet).  The  subject  was  put  on  the  re- 
breather  and  samples  of  the  alveolar  air  were  taken  every  4  or  5 
minutes  until  the  end  of  the  run.  The  time  and  the  oxygen  per  cent 
of  the  rebreathed  air  were  noted  and  the  corresponding  barometric 
pressure  for  each  oxygen  per  cent  determined.  The  same  subject  was 
taken  into  the  low-pressure  chamber  a  few  days  later  and  the  baro- 
metric pressure  was  lowered  according  to  the  rebreathing  schedule 
previously  made.  Alveolar  air  samples  w^ere  taken  at  corresponding 
minutes  and  altitudes.  Both  series  of  alveolar  air  samples  were 
analyzed  with  the  Henderson-Orsat  gas  analyzer  and  the  partial 
pressure  calculated  allow^ing  40  mm.  Hg.  for  the  tension  of  water 
A  apor.     The  curves  of  each  subject  were  plotted  on  the  same  chart. 

The  curves  of  the  alveolar  air  pressures  plotted  (see  chart  9a)  from 
the  data  obtained  in  the  low-pressure  chamber  and  with  the  re- 
breathing apparatus  are  striking  in  their  similarity.  In  many  cases 
they  practically  coincide.  The  oxygen  tension  in  the  alveolar  air  of 
eight  subjects  on  the  rebreathing  machine  fell  from  102.5  mm.  Hg. 
to  36.3  mm.  during  runs  from  760  mm.  to  350  mm.,  or  20.96  per  cent 
oxygen  to  9.8  per  cent.  This  is  an  average  fall  of  62.2  mm.  for  20,000 
feet  (see  Table  1).  In  10  corresponding  experiments  in  the  low- 
pressure  chamber  the  alveolar  oxygen  tension  fell  from  104.6  mm.  to 
35.8  mm.  during  the  ascent  to  20,000  feet.  The  average  fall  was 
08.8  mm.  (see  Table  2). 


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68 


AIR   SERVICE    MEDICAL. 


199 


In  the  previous  eight  cases,  in  which  the  alveolar  oxygen  pressure 
was  determined  on  the  rebreathing  apparatus,  the  alveolar  carbon 
dioxide  presvsure  fell  from  42.6  mm.  to  34.1  mm.,  an  average  fall  of 
8,5  mm.   (see  Table  3).     In  the  10  corresponding  cases  in  the  low- 


nuvEouARAiR  Pressures 

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pressure  chamber  the  alveolar  carbon  dioxide  tension  fell  from  40.1 
to  30.8  mm.,  an  average  fall  of  9.3  mm  (see  Table  4). 

The  curve  of  the  alveolar  oxygen  tension  obtained  in  the  low- 
pressure  chamber  or  on  the  rebreather  is  essentially  a  straight  line. 
That  of  the  alveolar  carbon  dioxide  tension  is  not  so  regular.  Certain 
irregularities  in  the  curve  were  found  which  could  be  correlated  with 
changes  in  lung  ventilation  as  indicated  by  the  volume  of  air  breathed 


200 


AIE  SERVICE  MEDICAL. 


per  minute.  In  seven  cases  there  was  a  gradual  fall  of  alveolar  carbon 
dioxide  pressure  as  the  barometric  pressure  was  lowered  from  760  mm. 
to  350  mm.  (20,000  feet).  In  two  cases  it  remained  nearly  constant 
until  about  550  mm.  and  then  fell  fairly  rapidly. 

An  examination  of  tables  1,  2,  3,  4,  and  of  the  plotted  curves  shows 
very  definitely  that  the  changes  of  the  alveolar  air  pressure  during 
exposure  to  progressively  diminished  oxygen  pressure  are  quite  simi- 
lar and  that  the  respiratory  factors  as  well  as  the  circulatory  and 
psychological  reactions  are  the  same  in  the  two  methods. 

Table  1. — Rehreathing  Os. 


Subject. 


Griest 

Browning... 

Pierce 

Burlingame. 

Jenkins 

Smart 

Kuempel 

MoKinnie. . . 


Average. 


760  nun. 


106.5 

106.0 

103.0 

109.0 

97.5 

99.0 

97.5 

101.2 


350  mm. 


39.^ 

33.8 
39.0 
38.0 
24.0 
38.0 
36.0 
42.0 


102.5 


36.3=66.2 


102.5  mm. 
36. 3  mm. 


Average  O2  tension,  760  mm , 

Average  Oj  tension,  350  mm 

Average  fall  for  20,000  feet  rise 66. 2  mm . 

Table  2. — Low  pressure  O3. 


Subject. 

760  mm. 

350  mm. 

Neuswanger 

116.7 
104.2 
94.5 
92.0 
104.5 
105.5 
108.0 
106.2 
106.2 
108.7 

33.4 

McKinnie  

38.0 

Dorsey 

34.4 

Smart 

36.0 

Merrill 

43.0 

Kuempel 

31.2 

Jenkins 

34.4 

Burlingame 

33.4 

Leiubach 

.36.1 

Pierce - - 

38.7 

Average 

104.6 

35. 8=68. 8 

Average  O3  tension,  760  mm. 
A  verage  Oj  tension,  350  mm. 


Average  fall  for  20,000  feet  rise. 


104.6  mm. 
35. 8  mm. 


68. 


1  mm. 


Table  3. — Rebreathing  CO2. 


Subject. 


Burlingame. 
Brownmg. . . 

Greist 

Pierce 

Jenkins 

Kuempel 

McKinnie. . . 
Smart 


760  mm. 


Average. 


43.5 
40.9 
42.4 
43.1 
45.6 
43.8 
39.2 
42.5 


350  mm. 


39.9 
35.4 
.39.3 
32.6 
18.0 
34.8 
33.0 
39.8 


42.6  !        34.1=  8.5 


42. 6  mm. 
34.1  mm. 


Average  CO3  tension,  760  mm 

Average  COj  tension,  350  mm 

Average  fall  for  20,000  feet  rise 8. 6  mm. 


ATE  SEBVIOE  MEDICAL. 


201 


Table  4 

. — Low  pressure  COj. 

Subject. 

760  mm. 

350  mm. 

Smart 

39.8 
41.2 
39.0 
38.7 
39.8 
40.4 
37.8 
40.0 
44.4 
40.4 

37  2 

Burlingame  

34  7 

Pierce 

30  4 

Jenkins 

27  3 

Kuempel 

24  4 

McKinnie 

31.6 

Leinbach 

27  6 

Merrill ... 

29  7 

Dorsey 

30  8 

Nftuswangfir  ,  . 

34  7 

Average 

40.1 

30.8—  9.3 

Average  CO2  tension,  760  mm 40. 1  mm. 

Average  CO2  tension,  350  mm 30. 8  mm. 

A  verage  fall  for  20,000  feet  rise 9. 3  mjn. 

From  these  preliminary  experiments  we  should  infer  that  in  the 
ordinary  short  experiments  in  which  the  barometric  pressure  is 
lowered  to  about  350  mm.  in  20  minutes,  similar  to  the  conditions 
during  a  rebreathing  test,  the  alveolar  carbon  dioxide  pressure  starts 
to  fall  with  the  barometer.  The  law  of  Haldane  and  Preistly,  which 
states  that  during  rest  under  ordinary  conditions  the  alveolar  carbon 
dioxide  pressure  remains  constant,  holds  good  only  when  the  baro- 
metric pressure  remains  constant  also.  These  experiments  point  to 
the  view  that  the  alveolar  carbon  dioxide  pressure  does  not  remain 
constant  under  progi'essively  diminished  barometric  pressure  to  the 
extent  formerly  believed. 

A  few  men  were  taken  to  15,000  feet  at  the  rate  of  1,000  feet  per 
minute,  held  there  for  five  minutes  and  then  dropped  at  the  same 
rate  to  2,000  feet.  This  procedure  was  repeated  three  times  in  suc- 
cession. The  alveolar  gas  pressures  were  remarkably  constant  for 
the  same  altitude  in  each  of  these  cases.  Table  5  gives  the  result 
in  two  such  cases. 

Table  5. 


Barometer. 

760  mm. 

425  mm. 

700  mm. 

425  mm. 

700  mm. 

425  mm. 

760  mm. 

,    fO. : 

104 
41 

106 
41 

40 
39 
51 
29 

91 
43 
96 
34 

40 
39 
47 
32 

92 
41 
95 
36 

39 
39 
48 
30 

QR 

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42 
95 

« 

In  a  number  of  experiments  the  subjects  were  exposed  to  low  oxy- 
gen tension  for  longer  periods.  Wlien  the  individual  is  held  for  an 
hour  or  more  at  a  low  barometric  pressure,  380  mm.  for  example 
(18,000  feet),  the  alveolar  air  pressures  tend  to  remain  remarkably 
constant.  In  10  cases  the  average  alveolar  carbon  dioxide  pressure 
at  the  end  of  96  minutes  was  only  about  1  mm.  lower  than  when  the 
low  barometric  pressure  was  first  reached.  The  fact  that  there  was 
no  striking  change  in  alveolar  carbon  dioxide  pressure  during  pro- 
longed exposure  to  a  given  low  barometric  pressure  led  us  to  examine 
the  volume  of  air  breathed  per  minute  during  these  exposures  and 
the  carbon  dioxide  capacity  of  the  blood  at  the  beginning  and  at 
the  end. 


202  AIE    SERVICE   MEDICAL. 

Eight  experiments  were  carried  out  to  determine  the  volume  of  air 
breathed  per  minute.  The  subject  wore  an  American  Tissot  mask  and 
inspired  through  a  gas  meter.  The  resistance  of  the  meter  was  not 
great  enough  to  cause  any  change  in  the  rate  or  vohime  of  respiration, 
as  shown  by  control  runs  for  periods  of  one  to  two  hours.  The  average 
volume  breathed  per  minute  at  760  mm.  was  7  liters.  With  the  ascent 
to  380  mm.  an  increase  in  ventilation  took  place,  attaining  its  maxi- 
mum about  10  minutes  after  the  low  barometric  pressure  had  been 
reached.  In  six  cases  of  these  eight  the  lung  ventilation  decreased 
more  than  a  liter  while  the  low  barometric  pressure  was  being  held. 
In  several  cases  the  breathing  decreased  to  its  original  volume  before 
the  ascent.  During  these  exposures  the  type  of  breathing  frequently 
changed  from  shallow  rapid  to  slow  and  deep  respiration.  In  one 
case  the  rate  fell  from  14  per  minute  to  9  within  20  minutes  after 
reaching  380  mm. 

During  short  exposures  to  progressively  diminishing  oxygen  pres- 
sure with  either  the  rebreather  or  in  the  low-pressure  chamber  the 
lung  ventilation  increases.  In  the  rebreathing  experiments  the  first 
respiratory  response  has  been  found  to  be  between  16  and  14  per  cent 
of  oxygen.  In  the  low-pressure  chamber  in  a  few  experiments  the 
response  in  breathing  occurred  at  about  8,000  feet,  or  at  approximately 
15  pel'  cent  of  oxygen.  In  several  instances,  however,  the  response 
began  immediately. 

CARBON   DIOXIDE  CAPACITY   OF  THE  BLOOD. 

Both  on  the  rebreathing  apparatus  and  in  the  low-pressure  cham- 
])er  the  carbon  dioxide  capacity  of  the  blood  was  determined  before 
the  experiment  and  at  the  end,  while  the  subject  was  still  under  the 
influence  of  low  oxygen.  On  the  rebreathing  apparatus  12  cases  were 
examined,  some  of  which  reached  6.2  per  cent  of  oxygen  and  showed  a 
marked  respiratory  reaction.  There  was,  however,  no  noticeable  low- 
ering of  the  carbon  dioxide  capacity  of  the  whole  blood  as  determined 
by  the  Henderson  method.  Even  in  the  low-pressure  chamber,  where 
the  subject  was  exposed  to  a  pressure  of  380  mm.  for  periods  of  over 
an  hour,  no  decreased  alkalinity  of  the  blood  could  be  detected.  This 
is  not  surprising  in  view  of  the  fact  that  the  volume  per  minute 
breathed  was  lowered  at  the  end  of  these  expei'iments. 

HEMOGLOBIN    CHANGES. 

One  of  the  factors  which  compensate  for  prolonged  exposure  to  low 
atmospheric  pressure  has  been  shown  to  be  the  hemoglobin.  On 
Pike's  Peak  a  relative  increase  in  the  per  cent  of  hemoglobin  takes 
place,  which  is  later  superseded  by  an  actual  increase  in  the  number 
of  red  cells.  The  ordinary  rebreathing  test  is  too  short  to  permit  of 
a  concentration  of  hemoglobin,  but  in  experiments  in  the  low-pres- 
sure chamber,  where  the  subject  is  held  for  periods  of  an  hour  or  two, 


ATE    SERVICE    MEDIC  AT, 


203 


a  Avell-defined  increase  has  been  found  with  the  Gower-Haldane 
hemoglobinometer  in  blood  taken  from  the  finger  and  from  the  vein 
in  more  than  25  per  cent  of  the  cases  examined.  In  several  cases  the 
amount  of  increase  was  more  than  6  per  cent  and  in  one  case  as  high 
as  9  per  cent.  In  a  few  instances  the  number  of  erythrocytes  was 
determined  and  an  increase  found,  which  in  one  case  was  9.6  per  cent 
and  in  another  case  14  per  cent. 

CHANGES  IN  PULSE  KATE  DURING  EXPOSURE  TO  LOW  OXYGEN  PRESSURE. 

In  a  series  of  experiments  in  the  low-pressure  chamber,  in  which 
the  barometric  pressure  was  lowered  to  380  mm.  (18.000  feet)  at  the 
rate  of  1,000  feet  per  minute  and  held  at  that  altitude  for  periods 
varying  from  60  to  104  minutes,  the  pulse  rate  was  taken  every  minute 
during  the  procedure.  The  curve  of  the  pulse  changes  plotted  against 
the  variation  in  the  barometer,  and  time  shows  that  the  rate  increases 
as  the  barometric  pressure  decreases,  but  does  not  maintain  its  maxi- 
mum during  the  hold  at  the  high  altitude. 

In  18  cases  out  of  20  there  was  a  slowing  of  the  pulse  rate  while 
the  low  pressure  was  being  maintained.  The  average  pulse  rate  at 
760  mm.  was  73  per  minute.  During  the  ascent  to  380  mm.  the 
average  increase  in  the  pulse  rate  was  19  beats,  or  about  1  beat  per 
1 ,000  feet.  This  increase  in  the  pulse  rate  began  between  2,000  and 
3,000  feet  in  an  average  of  34  cases.  In  only  4  cases  did  it  appear 
as  late  as  8,000  feet.     In  no  other  case  was  it  above  4,000  feet. 

The  maximum  pulse  rate  was  reached  in  24  minutes  after  the  be- 
ginning of  the  ascent,  or  6  minutes  after  the  barometric  pressure  of 
380  mm.  have  been  attained.  During  the  hold  of  this  altitude,  aver- 
aging 86  minutes,  the  average  pulse  slowed  to  84  beats  per  minute,  an 
average  drop  of  8  beats.  The  individual  decrease  in  pulse  rate 
varied  from  5  to  14  beats  and  in  7  of  the  20  cases  it  was  10  beats  or 
more.     (See  Table  6.) 

Table  6. — Change  in  pulse  rate  during,  exposure  to  low  oxygen  tension. 


Experiment. 

Normal. 

Maxi- 
mum. 

Time 
reached. 

Maxi- 
mum. 

Time 
reached. 

Fall. 

Total 
time. 

\       

'       64 
70 
65 
88 
75 
72 
71 
73 
78 
74 
69 
80 
59 
60 

81 
95 
67 
76 
72 
76   1 

91 
94 

102 
99 
89 
87 
86 
93 
94 

120 
87 

100 
80 
82 
88 
99 

88 
94 
82 

23 
31 
26 
25 
30 
22 
20 
22 
22 
24 
27 
22 
22 
24 
22 
25 
28 
26 
24 
22 

81 

86 
102 
93 
83 
82 
78 
81 
80 
106 
78 
90 
70 
74 
82 
99 
84 
81 
89 
71 

62 
76 
49 
81 
72 
82 
76 
75 
35 
56 
85 

54   1 
72   j 
77   ! 
64   ' 
80 

72   , 
81   ' 
68  I 
68   1 

10 

8 

1 

6 

6 

5 

8 

12 

14 

14 

9 

10 

10 

8 

6 

81 

2 

82 

3  

64 

4 

104 

5 

86 

6 

92 

7 

1   91 

g 

77 

9  

61 

10 

11 

68 
96 

12 

65 

13  

78 

14 

15 

16 

79 
78 
85 

17 

6 

7 

5 

11 

78 

18   

100 

19 

71 

20       

91 

A  vfirasTB 

73.25 

91.80 

24.35  1 

84.0 

69.2 

7.8 

85  76 

204  AIR  SEEVIOE  MEDICAL. 

THE  RELATIVE  VALUE  OF  THE  COMPENSATORY  FACTORS. 

The  factors  which  are  involved  in  the  compensation  during  very 
long  exposures  to  low-oxygen  pressures,  as  on  Pike's  Peak,  have  been 
shown  to  be,  first,  the  circulation,  as  indicated  by  the  pulse  rate  and 
the  blood  pressure;  second,  the  respiration,  as  shown  by  the  rate, 
volume  per  minute,  carbon  dioxide  and  oxygen  pressures  in  the  alve- 
olar air,  and  the  carbon  dioxide  capacity  of  the  blood;  third,  the 
hemoglobin;  fourth,  secretion  of  oxygen  by  the  lung  epithelium. 
Evidence  bearing  on  the  nature  of  the  first  three  factors  has  been 
secured  in  these  experiments.  There  is  undoubtedly  a  considerable 
amount  of  coordination  and  interplay  of  the  various  factors.  In 
the  rebreathing  tests  the  circulation  responds  first,  later  the  respira- 
tion. In  these  tests  the  subject  is  pushed  until  he  shows  signs  of  fail- 
ing in  compensation.  The  situation  is  different  when  the  individual 
is  kept  at  a  given  low  pressure  in  the  pneumatic  chamber.  Both  the 
pulse  and  the  respiration  acceleiate  during  the  ascent,  but  in  a  great 
many  cases  the  pulse  rate  falls  while  the  chosen  pressure  is  being 
maintained.  We  should  look  for  compensation  by  other  factors  in 
these  cases,  either  by  means  of  increased  lung  ventilation,  concentra- 
tion of  hemoglobin,  or  possibly  secretion  of  oxygen  through  the 
lung  epithelium.  In  a  number  of  men  the  heart  was  relieved  by  fur- 
ther deepening  of  the  breathing  or  a  concentration  of  the  hemo- 
globin, or  both  changes  occurred.  A  number  of  cases  have  been  ob- 
served in  which  a  concentration  of  hemoglobin  took  place  while  the 
heart  rate  slowed  (see  chart  10a),  and  the  lung  ventilation  either 
maintained  its  own  or  became  less. 

An  unusual  but  interesting  case  wafe  found  in  a  man  whose  breath- 
ing failed  to  respond  to  the  change  in  altitude.  He  did  not  tolerate 
the  low  pressure  well  at  first,  but  later  his  condition  improved  while 
the  given  low  pressure  was  being  maintained.  The  heart  rate  accel- 
erated markedlj^  and  later  his  hemoglobin  concentrated  above  8 
per  cent.  His  improvement  occurred  Avhen  his  heart  was  relieved  by 
the  concentration  in  hemoglobin. 

Our  studies  show  that  during  short  exposures  to  high  altitudes  or 
low  oxygen,  such  as  the  aviator  experiences,  the  compensatory  re- 
actions of  the  body  are  made  almost  entirely  by  the  circulation  and 
the  breathing.  Some  men  may  secure  some  benefit  after  an  hour  or 
more  from  a  slowly  developing  concentration  of  the  hemoglobin  of 
the  blood.  The  order  of  response  by  the  adaptive  mechanisms  is  not 
that  of  the  good  response  seen  among  mountaineers,  in  whom  the 
breathing  first  responds  while  the  other  compensatory  changes  more 
slowly  occur.  The  reaction  resembles  more  nearly  that  seen  during 
an  attack  of  mountain  sickness  among  moimtaineers.    In  such  men 


AIR  SERVICE   MEDICAL. 


205 


the  heart  beat  is  greatly  accelerated  during  the  attack.  The  aviator 
must  depend  largely  on  his  heart  and  his  breathing  for  compensation 
to  the  fall  in  oxygen  pressure  which  he  encounters  during  an  ascent. 

III.— THE  EFFECTS   OF   LOW   ATMOSPHERIC   PRESSURE   ON   THE 

CIRCULATORY  SYSTEM. 

It  has  long  been  recognized  in  an  unscientific  way  that  high  alti- 
tudes are  "bad  for  a  weak  heart."  At  such  elevations  as  those  of 
Denver,  Phoenix,  or  Mexico  City,  patients  with  any  degree  of  cardiac 
incompetence  noticed  undue  shortness  of  breath,  palpitation,  general 
weakness,  and  occasionally  there  have  been  cases  of  sudden  decom- 
pensation and  acute  pulmonary  congestion.     Even  much  lower  eleva- 


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Chabt  10a. 

tions  have  been  suspected  by  the  laity  of  causing  distinct  heart  symp- 
toms. The  reason  for  this  has  not  been  understood,  because  very 
little  research  work  from  this  point  of  view  has  been  carried  on.  The 
physiological  results  on  Monte  Rosa,  Pike's  Peak,  etc.,  have  had  as 
participants  and  subjects  almost  entirely  health}^  men  of  the  moun- 
taineering type,  and  in  these  there  has  been  so  little  evidence  of  cir- 
culatory strain,  to  say  nothing  of  actual  incompetence,  that  it  was 
generally  assumed  that  the  supposed  dangei's  from  the  heart  were 
mythical  or  at  least  much  exaggerated. 

As  a  part  of  the  research  now  being  carried  on  at  the  Medical 
Research  Laboratory  of  the  Air  Service  at  Mineola  the  behavior  of 


206  AIB    SERVICE   MEDICAL. 

the  heart  and  circulation  has  received  much  attention.  We  have 
had  almost  ideal  conditions  for  this  study,  having  at  our  disposal 
two  methods  of  producing  phj'siological  effects  comparable  to  those 
of  aviation.  In  these  effects  the  determining  factor  is,  of  course,  low- 
oxygen  tension'in  the  air. 

In  the  rebreathing  apparatus  the  percentage  of  oxygen  is  grad- 
ually lowered,  while  in  the  low-pressure  chamber  the  percentage 
remains  the  same,  but  the  barometric  pressure  may  be  reduced  to 
any  desired  point.  In  either  case  accurate  observations  of  heart  and 
circulation  are  conveniently  made.  The  two  methods  give  strictly 
parallel  results,  which  tally  very  accurately  with  actual  conditions 
in  the  air  as  far  as  it  has  been  possible  to  investigate  the  latter 
directly  or  to  judge  from  what  is  told  by  aviators  of  their  own 
experience.  The  material  studied  has  consisted  largely  of  healthy 
and  youthful  individuals,  though  even  among  supposedly  normal 
men  not  a  few  pathological  hearts  have  been  discovered,  and  from 
the  neighboring  post  hospitals  we  have  obtained  a  few  subjects  who 
were  known  to  have  definitely  abnormal  hearts.  In  the  near  future 
we  hope  to  extend  very  considerably  our  observations  on  the  grosser 
forms  of  valvular  and  mvocardial  disease  and  on  cases  with  various 
degrees  of  decompensation. 

The  results  have  been  exceedingly  interesting  and  important  and 
have  so  fitted  in  with  the  experiences  and  the  problems  of  aviators 
that  they  can  not  but  be  of  the  greatest  practical  value.  They  have 
shown  that  the  ability  to  exist  at  altitudes  higher  than  the  normal 
depends  to  a  very  marked  degree  on  the  competence  of  the  circula- 
tor}'^  apparatus.  The  demand  on  the  latter  is  so  great  that  even 
slight  abnormalities  in  heart  or  blood  vessels  result  at  moderate 
heights  in  clear  signs  of  cardiac  insufficiency  and  distress.  So 
searching  indeed  is  this  test  for  cardiac  disease  of  any  kind  that  we 
have  come  to  regard  the  rebreathing  apparatus  and  the  low-pressure 
chamber  as  the  one  sure  way  of  making  a  positive  diagnosis  in  cases 
where  there  is  doubt,  and  believe  that  they  may  later  prove  to  be  of 
great  value  for  routine  clinical  work. 

At  the  same  time  the  effects  upon  the  normal  heart  have  been 
equally  striking  and  more  unexpected.  While  the  hardiest  type  of 
subject  shows  almost  no  demonstrable  effect  on  the  circulation,  others 
are  evidently  laboring  under  heavy  strain,  and  it  appears  that  dilata- 
tion of  the  heart  followed  by  collapse  is  an  extremely  common  oc- 
currence even  at  moderate  altitudes.  This  accords  with  the  known 
frequency  of  aviators  fainting  in  the  air,  almost  always  with  fatal 
results,  of  course.  We  have  been  able  to  throw  much  light  on  the 
reasons  for  this  disastrous  occurrence,  and  to  show  not  only  that  evi- 
dent disturbances  of  heart  frmction,  such  as  cardiac  lesions,  are  predis- 
posing causes,  but  that  temporary  indispositions  which  are  too  fre- 


AIR   SERVICE   MEDICAL.  207 

quently  considered  trivial  have  a  very  marked  influence.  For  exam- 
ple, a  recent  infection,  a  bad  cold,  nervous  factors,  etc,  may  so  im- 
pair a  man's  resistance  that  his  heart  will  give  out  and  he  will  faint 
ihirino;  the  test.  We  believe  that  this  has  actually  occurred  in 
•  lumerous  cases  during  actual  flight. 

It  has  been  estimated  in  the  British  Service  that  of  all  fliers  lost  to 
active  flying  service  less  than  2  per  cent  are  put  out  by  Gorman  bullets, 
only  8  per  cent  as  the  result  of  a  defect  in 'the  plane,  tiie  remaining  90 
per  cent  because  of  the  physical  condition  of  the  pilot.  Our  work 
leads  us  to  believe  that  a  considerable  proportion  of  the  physical 
defects  leading  tO  accident  are  the  immediate  or  late  effects  of  strain 
on  the  circulation  under  the  influence  of  low  oxygen  tension  in 
the  air. 

PHYSIOLOGY  or  CIRCULATIOX. 

The  purpose  of  the  heart  and  blood  vessels  is  to  transport  oxygen 
and  food  to  the  tissues  and  to  remove  their  waste.  The  work  of  the 
circulatory  system  must  be  governed  hy  the  changing  needs  of  the 
tissues  in  these  respects.  If  a  given  group  of  muscles,  for  example, 
are  doing  more  than  their  usual  work  they  must  have  an  increase  of 
blood  supply.  Thi^^  regulation  comes  mainly  from  the  vital  centers 
in  the  medulla,  and  consists  for  the  most  part  in  variations  in  the 
size  of  blood  vessels  (vasomotor  tone),  in  the  rate  of  the  heart,  and 
in  the  amount  of  lung  ventilation.  The  medullary  centers  are  in 
turn  -activated  by  certain  chemical  factors  in  the  blood,  and  probabh^ 
:ilso  more  directly  by  their  own  metabolism  and  need  for  oxygen. 

The  work  done  by  the  heart  is  very  large  even  when  the  body  is  at 
rest.  It  has  been  calculated  that  this  amounts  in  ordinary  conditions 
to  the  work  involved  in  lifting  20  kilogram  one  meter  each  minute 
or  about  140  pounds  1  foot.  During  exercise  this  work  is,  of  course, 
much  increased. 

Apart  from  the  strain  thrown  upon  the  heart  by  extraordinary 
demands  it  is  evident  that  even  its  ordinary  work  requires  the  best 
of  conditions  to  be  carried  successfully.  Heart  failure  may  be  the 
result,  therefore,  not  only  of  extra  work  asked  of  the  heart,  but  of 
any  condition  which  interferes  with  its  success  in  doing  its  ordinary 
work. 

The  efficiency  of  the  heart  depends,  first,  on  the  quality  of  the 
heart  muscle;  second,  on  an  abundant  coronary  circulation,  capable 
not  only  of  supplying  ordinary  needs,  but  of  meeting  the  demand  for 
considerable  increase;  third,  on  the  quality  of  the  blood  which 
nourishes  the  heart  muscle,  especially  its  content  in  oxygen;  and 
fourth,  on  an  economical  regulation  of  the  work  of  the  heart  and  of  all 
of  the  elements  in  circulation  and  respiration,  so  that  these  functions 
may  be  carried  out  successfully,  but  without  unnecessary  strain.    The 


208  AIB  SEEVIOE  MEDICAL. 

last  factor  depends  partly  on  the  accuracy  and  economy  with  which 
the  need  for  blood  flow  to  each  part  of  the  body  is  met,  and  partly  to 
the  regulation  of  general  vascular  tone,  so  that  the  blood  flow  can 
take  place  to  the  maximum  of  efficiency  without  undue  resistance 
(increased  blood  pressure). 

EFFECT  OF  LOW  OXYGEX  TENSION  ON  CIRCULATORY  PHYSIOLOGY. 

The  behavior  of  the  organism  under  low  pressure  illustrates  two 
physiological  principles : 

First,  that  the  animal  body  being  very  accurately  fitted  for  one  set 
of  environmental  conditions,  finds  itself  in  an  abnormal  situation 
if  these  conditions  are  changed  ever  so  slightly.  We  know  that  the 
body  feels  the  change  in  its  oxygen  supply  within  the  first  few 
thousand  feet,  perhaps  even  the  first  few  hundred  feet  after  ascent 
begins  from  the  surface  of  the  earth.  In  consequence  of  this  certain 
readjustments  and  compensations  are  necessary  to  keep  the  oxygen 
tension  in  the  air. 

The  second  principle  is  that  however  accurately  the  body  is  ad- 
justed to  its  usual  surroundings,  its  powers  of  accommodation  to  new 
conditions  are  very  great,  even  when  those  conditions  represent  some- 
thing quite  out  of  the  ordinary  experience  of  the  body.  Thus  when 
adjustments  are  demanded  to  make  good  oxygen  deficiency  in  the 
atmosphere,  such  adjustments  almost  infallibly  will  be  made  and  in 
sufficient  abundance  to  keep  bodily  functions  normal  until  the  change 
from  usual  conditions  has  become  so  great  that  the  powers  of  com- 
pensation are  exhausted. 

In  other  words,  the  aviator  making  an  ascent  to  great  heights  gives 
the  picture  not  of  a  man  suffering  more  and  more  severely  from  the 
noxious  effects  of  low  oxygen  but  of  a  man  who  by  exercising  his 
powers  of  compensation  is  keeping  his  functions  normal  just  as  long 
as  these  powers  remain  equal  to  their  task. 

It  was  in  fact  a  good  deal  of  a  surprise  to  us  to  find  this  unex- 
pected normality  of  our  subjects  in  the  early  experiments,  for  not 
only  were  the  physical  and  psychic  powers  being  kept  intact  until 
an  extreme  degree  of  oxygen  want  was  reached,  but  the  adjustment 
was  so  smoothly  and  economically  made  that  our  examination  of 
heart  and  blood  vessels  and  the  respiratory  phenomena  would  have 
led  us  to  suppose  that  nothing  out  of  the  ordinary  was  going  on  at  all. 

This  statement  applies,  however,  only  to  what  we  may  refer  to  as 
the  "  optimum  "  type  of  subject,  and  it  was  only  by  observing  the 
behavior  of  less  good  subjects  that  we  arrived  at  an  understanding 
not  only  of  the  nature  of  the  compensation  which  was  making  this 
normality  possible,  but  of  the  very  great  strain  which  is  often  in- 
volved in  maintaining  it.    For  while  our  optimum  subjects  remained 


AIB   SERVICE  MEDICAL.  209 

in  good  condition  and  efficient  to  very  great  heights  and  at  the  same 
time  exhibited  no  signs  of  strain  in  the  circulatory  reactions  other 
subjects  either  failed  to  make  the  compensation  and  so  became  in- 
efficient at  low  altitudes  or  made  the  compensation  only  at  the  cost 
of  very  evident  strain,  such  as  led  in  many  cases  to  cardiac  dilatation, 
circulatory  collapse,  and  fainting. 

COMPENSATION  FOR  OXYGEN,  DEFICIENCY. 

We  must  first  discuss  the  nature  of  the  compensating  process  and 
later  consider  how  different  t3'pes  of  organisms  respond  to  this 
demand. 

"^ATien  the  tissues  feel  a  deficiency  in  the  oxygen  supply,  demand 
is  immediately  registered  for  more.  Just  how  this  deficiency  is  felt 
and  what  the  nature  of  the  demand  is  we  need  not  discuss  at  this 
point.  (As  a  matter  of  fact,  we  have  very  little  knowledge  on  the 
subject.)  It  is  sufficient  that  such  demand  is  made  and  that  it  is 
promptly  complied  with. 

"^Vhen  there  is  deficiency  in  the  oxygen  carried  by  the  blood  there 
are  two  obvious  methods  of  remedy  open — either  (a)  more  oxygen 
must  be  carried  by  the  same  amount  of  blood  or  (&)  more  blood 
must  flow  to  the  tissues  carrying  less  oxygen  per  unit  but  in  sum 
bringing  the  required  amount. 

INCREASED  RESPIRATION. 

To  meet  the  demand  of  (a),  if  the  blood  carries  less  oxygen  per 
unit  because  of  lowered  tension  in  the  alveolar  air,  this  tension  may 
be  raised  by  increased  ventilation  of  the  lungs.  Normally  the  per- 
centage of  oxygen  in  the  alveolar  air  (that  which  comes  in  contact 
with  the  blood)  is  from  13  to  15  per  cent,  giving  a  tension  of  100 
or  more  mm.  Hg.  Increased  respiration  will  raise  this  percentage 
to  17,  18,  or  even  19,  thus  increasing  the  oxygen  tension  in  the  blood 
to  a  like  degree.  In  fact,  we  know  that  increase  in  respiration  begins 
to  occur  almost  as  soon  as  the  sea-level  pressure  is  left  behind. 

The  limit  of  compensatory  mechanism  is  soon  reached  however. 
Since  the  atmosphere  contains  only  21  per  cent  oxygen,  the  alveolar 
air  can  only  with  difficulty  be  brought  up  to  19  per  cent,  and  an 
increase  from  15  to  19  per  cent  will  certainly  not  compensate  for  a 
drop  in  atmospheric  pressure  of  one-half,  such  as  occurs  when  a 
height  of  18,000  feet  has  been  reached. 

INCREASED  BLOOD  FLOW. 

The  second  method  will  be  more  productive  of  results.  Instead  of 
providing  the  normal  amount  of  blood  with  the  usual  burden  of 
oxygen  an  increased  blood  flow  with  a  lessened  amount  of  oxygen 
per  unit  will  answer  as  well. 


210  AlK   SERVICE   MEDICAL. 

Increased  blood  flow  is  accomplished  in  two  ways.  There  must 
be  peripheral  relaxation  of  the  arteries  to  allow  more  blood  to 
pass,  and  there  must  be  increase  in  the  amount  of  blood  coming  from 
the  heart.  The  latter  is  accomplished  either  by  increase  in  pulse 
rate  (more  beats  per  minute  delivering  the  normal  volume)  or  bj' 
increase  in  volume  output  per  beat.  Increase  in  heart  output  by 
either  method  would,  of  course,  tend  to  raise  the  blood  pressure. 

It  may  be  emphasized  that  a  very  considerable  increase.  p(;ssibly 
a  doubling,  of  the  blood  flow  may  be  accomplished  with  very  little 
evidence  that  this  is  taking  place,  since  the  various  mechanisms 
for  accomplishing  it  interplay  in  such  a  fashion  as  to  hide  each 
others'  traces.  Thus  increase  of  pulse  may  be  made  unnecessary  by 
increase  of  volume  per  beat  (it  is,  however,  still  a  controversial  ques- 
tion how  much  the  latter  can  vary).  Again,  increase  of  heart  out- 
put must,  of  course,  raise  the  blood  pressure,  while  decrease  in 
peripheral  resistance  (vasodilatation)  lowers  it  again.  We  have 
reason  to  believe  that  for  a  given  organism  a  certain  blood  pressure 
is  optimum,  combining  efficiency  with  economy,  and  that  the  body 
tries  to  keep  to  this  pressure  as  closely  as  possible.  For  this  reason  the 
best  type  of  subject  will  show  almost  no  change  in  either  systolic  or 
diastolic  pressure  until  late  in  the  experiment,  when  the  powers  of 
compensation  are  being  pushed  to  the  limit. 

1U5LATI0N  OF  VASOMOTOR  CONTROL  OF  THE  HEART. 

A  thorough  understanding  of  the  interplay  between  heart  and  blood 
vessels  is  necessary  in  order  to  comprehend  the  adjustment  and  fail- 
ures of  adjustment  occurring  on  exposure  to  low  oxygen.  In  every- 
day life  this  interplay  is  constantly  going  on;  the  better  the  condi- 
tion of  the  heart  muscle  and  of  the  arteries  and  the  better  the  nervous 
control  the  more  successful  will  the  organism  be  in  keeping  up  its 
efficiency.  Every  effort,  such  as  rising  from  a  chair  or  running  for  a 
street  car,  even  ever}'  emotion,  calls  for  increase  of  blood  flow  and 
would  inevitably  give  rise  to  increase  of  blood  pressure  and  extra 
work  for  the  heart  if  vasodilatation  did  not  ease  the  strain  and  at 
the  same  time  allow  the  increased  flow.  A  young  man  with  good 
arteries  can  exert  fairly  ^  iolent  muscular  efforts  with  moderate  and 
transitory  rise  in  pulse  and  blood  pressure.  An  older  man,  however, 
whose  arteries  are  less  flexible,  can  not  do  this.  In  his  case  the  blood 
])ressure  may  increase  to  a  dangerous  point  because  of  failure  of  the 
peripheral  tone  to  relax.  The  result  of  this  failure  will  be  either  that 
the  heart  is  put  upon  a  dangerous  strain  or  that  the  demands  are 
simply  not  met.  In  the  latter  case  the  organism  will  for  the  time 
being  have  to  run  with  a  deficit;  hence  loss  of  efficiency  and  symptoms 
of  deficient  circulation  (dyspnea,  cyanosis.  Aveakness,  etc.). 


AIR  SERVICE   MEDICAL.  211 

NERVOUS  FACTORS  IN  VASOMOTOR  CONTROL. 

The  nervous  element  in  the  control  of  the  vasomotors  is  of  great  im- 
portance. It  is  well  known  that  the  vasomotor  system  is  the  most 
sensitive  part  of  the  body.  The  slightest  emotion  will  cause  flushing 
or  pallor,  or  even  an  anemia  of  the  brain,  which  leads  to  fainting.  The 
nervous  regidation  is  especially  under  the  influence  of  lack  of  "  con- 
dition "  from  various  causes,  such  as  infections,  indigestion,  lack  of 
sleep,  etc.  If  a  man  is  out  of  condition  a  slight  effort  will  cause  twice 
the  rise  in  pulse  and  blood  pressure  that  it  normally  should,  and  this 
rise  will  last  much  longer. 

There  are  observations  to  show  that  pureh'^  nervous  factors,  such 
for  instance  as  great  mental  concentration,  will  cause  a  higher  and 
more  lasting  rise  than  severe  muscular  exertion.  This  is  presumably 
because  in  phj'sical  exertion  vasodilatation  will  provide  for  the  extra 
blood  flow  needed  with  very  little  necessity  for  increasing  the  blood 
pressure.  Where  nervous  tension  is  at  a  high  pitch,  however,  the 
vasomotors  are  certain  to  share  in  this  tension.  Peripheral' resistance 
will  be  high  and  the  blood  picssure  will  be  high  and  sustained.  Pres- 
sures of  200  have  been  observed  in  young  men  as  a  result  of  mental 
work  or  excitement,  and  such  a  pressure  may  last  for  an  hour  or 
more,  often  until  peripheral  relaxation  has  been  brought  about  by 
such  means  as  vigorous  muscular  exercise,  a  hot  bath,  etc.  We  shall 
see  later  that  this  psychic  reaction  of  peripheral  vascular  tension 
(and  of  increased  heart  rate  as  well)  has  a  marked  influence  on  the 
ability  to  withstand  low  oxygen. 

In  the  normal  organism  the  amount  of  blood  flow  will  not  only 
be  regulated  as  to  total  amount,  but  there  will  be  accurate  division 
according  to  the  needs  of  the  various  parts  of  the  body. 

The  aviator  is  not  using  his  muscles  to  a  great  extent,  so  does 
not  need  a  great  increase  in  blood  flow  here,  though  the  deficiency 
in  oxygen  is  probably  felt  to  some  extent  in  all  the  tissues  and  the 
blood  flow  to  all  parts  of  the  body  may  need  to  be  increased  some- 
what. Two  parts  of  the  body  however,  must  be  especially  taken  care 
of — the  brain  centers  which  feel  the  want  of  oxygen  and  are  regu- 
lating its  supply  and  the  heart  muscle  which  is  doing  more  than  its 
ordinary  work.  It  is  probable  that  one  important  difference  between 
the  "  optimum  "  type  and  the  type  who  overcompensates  and  strains 
his  circulation  is  that  the  former  keeps  brain  and  heart  well  sup- 
plied with  blood  but  does  not  flood  the  rest  of  his  body,  while  the 
latter  has  a  marked  increase  of  flow  to  all  parts  and  so  throws  this 
unnecessary  extra  work  upon  the  heart. 

89118—19 ^15 


212  ATE  SEEVICE  MEDICAL. 

FAILUBE  TO  COMPENSATE. 

It  has  already  been  suggested  that  when  circumstances  arise  calling 
for  a  compensation  involving  heart  strain  certain  hearts  will  respond 
with  the  necessary  effort  even  to  their  own  detriment,  while  certain 
others  will  give  up  the  task  at  once  and  allow  physical  inefficiency 
to  result.  The  difference  is  partly  one  of  condition  of  the  heart 
muscle  and  general  physical  tone,  and  partly  of  the  quickness  and 
efficiency  of  the  nervous  reactions  which  govern  the  vital  functions. 
The  same  principle  applies  to  the  whole  body,  even  to  the  person- 
ality, as  well  as  to  the  heart  alone.  One  individual  will  drive  at 
business,  athletics,  etc.,  with  an  intensity  which  brings  success,  but 
often  at  the  cost  of  health ;  another  will  save  his  health  but  lose  the 
game  or  the  business  deal. 

This  conception  is  necessar\-  in  understanding  the  reaction  to  low 
oxygen.  One  subject  will  compensate  fully  with  strain  if  it  is  neces- 
sary; the  other  will  very  early  give  up  the  effort  and  his  efficiency 
will  be  correspondingly  early  impaired.  Inasmuch  as  the  strain  is 
most  vitally  felt  in  the  circulatory  apparatus  it  follows  that  the  sub- 
jects who  are  most  vigorous  in  adjusting  themselves  to  the  new  con- 
(iition  will  show  cardiac  exhaustion,  while  those  who  show  early  in- 
efficiency will  not.  Furthermore,  a  man  who  shows  early  inefficiency 
can  still  go  on  with  the  experiment,  becoming  more  and  more  ineffi- 
cient, but  not  straining  his  heart.  The  man  who  compensates,  in  other 
words,  frequently  gives  out  from  heart  or  vasomotor  exhaustion 
(faints)  while  the  man  who  does  not  so  compensate  may  remain  more 
or  less  in  possession  of  his  faculties  to  a  much  higher  altitude.  This 
result  seems  paradoxical  since  the  former  class  are  individuals  who 
are  physically  far  superior  to  the  latter. 

INSUFFICIENT  COMPENSATION. 

It  is  to  be  assumed,  of  course,  that  no  organism  will  fail  to  make 
any  efforts  to  adjust  itself  to  altered  conditions.  We  have,  however, 
encountered  a  few  individuals  whose  reactions  have  been  almost  nil. 
Such  men  show  no  demonstrable  rise  in  pulse,  no  change  in  blood 
pressures,  and  none  in  respiration.  From  this  one  could  predict  that 
the  psychological  tests  (the  best  criterion  we  have  as  to  the  suffi- 
ciency of  the  compensation)  will  show  early  deterioration.  We  have 
observed  "  complete  inefficiency  "  in  a  few  case's  as  low  as  6,000  feet 
(or  at  the  corresponding  oxygen  percentage).  Such  men  are  usually 
constitutionally  inferior,  often  undersize,  with  poor  chests,  poor 
color,  clammy,  mottled  hands,  poor  complexion,  etc. 

In  addition  to  these  types  of  constitutional  inferiority  similar  lack 
of  reaction  will  be  shown  by  many  men,  especially  those  toward  mid- 
dle age,  who  have  led  a  sedenetary  life,  are  overweight  and  flabby, 


AIK   SERVICE   MEDICAL.  213 

perhaps  with  fatty  hearts.  In  these  cases  it  might  be  expected  that  a 
good  course  of  physical  training  would  much  improve  their  reactions. 
It  has  long  been  recognized  on  Pike's  Peak  that  the  visitors  of  athletic 
type  and  in  good  training  are  much  less  likely  than  others  to  be  moun- 
tain sick. 

It  is  not  to  be  expected  that  either  of  these  types  will  commonly 
be  found  among  a  class  so  carefullj'^  selected  as  aviators.  Less  degrees 
of  inability  to  compensate,  hoAvever,  are  not  uncommonly  found.  All 
ihese  cases,  of  course,  follow  the  rule  that  the  less  vigorous  the  com- 
pensation the  less  likely  the  subject  is  to  show  heart  strain. 

THE  "  OPTIMUM  "  TYPE. 

At  the  other  extreme  is  the  "  optimum  "  type  for  aviation,  those 
who  compensate  fully  to  very  great  altitudes,  retaining  their  effi- 
ciency and  yet  doing  this  in  so  accurate  and  economical  a  fashion 
from  the  point  of  view  of  the  circulation  that  there  is  little  or  no 
evidence  of  strain.  When  the  break  comes  (above  25,000  feet  in  the 
low-pressure  tank,  at  from  5.5  to  7  per  cent  on  the  rebreathing  appa- 
ratus) it  comes  with  great  suddemiess;  from  almost  full  efficiency 
there  is  a  quick  lapse  into  unconsciousness,  but  still  with  no  circula- 
tory collapse.  There  is  no  loss  of  general  muscular  tone;  the  subject 
remains  sitting  with  eyes  open,  stylus  held  firmly  in  hand,  color  full, 
though  of  course  cyanotic,  pulse  full  and  regular,  systolic  and  dia- 
stolic pressures  maintained.  Kecovery  is  almost  instantaneous  on 
return  to  normal  oxygen  pressure  and  is  complete.  The  subject 
usually  refuses  to  believe  that  he  has  not  been  conscious  and  efficient 
throughout.  We  must  attribute  this  unconsciousness  to  direct  action 
of  low  oxygen  on  the  cortical  centers  while  the  circulation  is  still  in 
order. 

CIRCULATORY  COLLAPSE. 

Quite  different  is  the  picture  when  circulatory  failure  has  occurred ; 
cardiac  dilatation,  sudden  collapse  of  vascular  tone,  ashy  pallor,  cold 
sweat,  complete  loss  of  muscular  tone,  so  that  the  subject  always  falls 
from  his  chair.  Recovery  is  slow  and  unsatisfactory;  it  is  often 
an  hour  before  the  man  is  himself  again.  Circulatory  collapse  may 
be  seen  at  any  stage  of  the  experiment,  depending  on  the  amount  of 
strain  preceding  it,  and  occasionally  comes  on  most  unexpectedly. 

HEART  STRAIN. 

The  syndrome  of  heart  strain,  followed  by  dilatation  and  fainting, 
is  of  very  great  importance  in  aviation.  We  know  that  fainting  in 
the  air  is  common  and  that  such  an  occurrence  is  practically  always 
fatal.    We  know  also  that  aviators  almost  invariably  develop  in  time 


214  AIE  SERVICE   MEDICAL. 

a  disabling  "  staleness,"  which  we  strongly  suspect  is  the  result  of  this 
recurring  heart  strain,  and  that  fliers  who  have  "gone  stale"  are 
particularly  sensitive  to  low  oxygen  and  particularly  liable  to  dila- 
tation and  fainting. 

That  heart  strain  is  common  was  shown  during  a  recent  demonstra- 
tion of  the  low-pressure  chamber  to  a  group  of  medical  officers,  men 
certainly  of  average  health,  though  not  in  the  best  of  training.  Five 
men  were  taken  into  the  tank  and  of  these  two  had  acute  heart  symp- 
toms and  had  to  take  oxygen  before  20,000  feet  was  reached.  The 
following  day  five  more  men  underwent  the  test ;  one  had  a  dilatation 
at  14,000  feet,  another  at  16,000  feet,  and  a  third  at  18,000  feet.  In 
other  words,  just  half  of  a  group  of  ordinary  subjects  showed  this 
very  striking  effect.  It  was  interesting  that  in  each  case  the  dilata- 
tion was  demonstrated  by  percussion  while  the  subject  still  felt  per- 
fectly well,  according  to  his  statement,  but  in  each  case  he  began  to 
feel  ill  before  a  minute  had  passed  and  would  have  fainted  if  oxygen 
had  not  been  given  promptly. 

Let  us  summarize  what  has  already  been  said  as  the  incidence  of 
heart  strain;  the  "optimum"  subjects  do  not  show  it,  either  because 
they  have  a  strong  heart  muscle  or  because  their  compensation  is 
made  so  economically  as  to  throw  a  minimum  of  work  on  the  heart. 
The  poor  types  of  reactors  (those  whose  compensation  is  of  low 
grade)  do  not  show  it,  because  their  hearts  are  not  being  asked  to 
overwork.  Subjects  with  defective  heart  muscle  do  not  show  it,  be- 
cause their  hearts  refuse  to  overwork.  Those  who  do  show  it  are 
young  men  of  quick  reaction,  usually  of  excellent  constitution,  though 
often  "  out  of  condition."  Such  subjects  often  have  a  marked  psychic 
reaction  from  the  start,  with  rise  in  pulse  and  blood  pressure,  indicat- 
ing undue  tension  of  the  nervous  system.  When  one  listens  to  the 
heart  it  is  evident  almost  from  the  start  that  this  organ  is  working 
too  hard ;  at  first,  perhaps,  with  plenty  of  reserve,  but  later  the  limit 
is  passed  and  there  is  a  sudden  break. 

What  is  the  essential  difference  between  the  "  optimum  "  type  and 
what  might  be  called  the  "  next  to  the  optimum  type,"  by  which  the 
one  shows  no  circulatory  exhaustion  up  to  the  point  of  unconscious- 
ness while  the  other  breaks?  It  is  partly  strength  and  quality  of 
heart  muscle  and  ability  to  stand  strain ;  it  is  partly  a  smooth  work- 
ing of  the  nervous  regulation  of  heart  and  blood  vessels,  including 
freedom  from  high  nervous  tension ;  it  is  partly  the  ability  to  furnish 
an  abundant  circulation  through  the  coronary  vessels  when  need 
arises.  It  can  be  expressed  in  one  word  familiar  to  physical  trainers, 
"  condition."  If  we  knew  just  what  "  condition  "  means  we  should 
have  the  answer  to  the  question  above. 


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AIR   SERVICE   MEDICAL.  216 

CONDITION. 

We  imagine  the  chief  elements  in  athletic  condition  are  a  strong 
heart  muscle,  a  highly  efficient  coronary  circulation,  and  good  periph- 
eral vasomotor  control.  We  may  guess  that  there  may  be  even  deeper 
factors,  such  as  a  difference  in  the  chemistry  of  the  tissues  allowing 
rapid  metabolism,  and  the  ability  to  generate  energy  rapidly  without 
the  accumulation  of  harmful  end  producjis.  At  any  rate,  our  work 
strongly  emphasizes  the  necessity  for  keeping  aviators  as  nearly  as 
possible  in  perfect  physical  condition  and  preventing  them  from  fly- 
ing when  they  are  not  so.  We  believe  they  should  daily  be  made  to 
exercise  in  such  a  wsij  that  the  heart  will  have  to  work  harder,  the 
coronarv  vessels  deliver  a  full  volume  of  blood,  the  vasomotors  be 
practiced  in  their  work,  the  respiration  deepened,  and  metabolism 
kept  going  at  an  increased  rate. 

TEMPORARY   INDISPOSITIONS. 

By  "  lack  of  condition  "  we  mean  not  only  "  softness  "  due  to  lack 
of  exercise,  but  many  temporary  indispositions,  such  as  may  follo\v 
a  bad  cold,  recent  illness,  lack  of  sleep,  overwork,  alcoholic  excess, 
etc.  The  influence  of  such  factors  on  abilitv  to  withstand  low  oxvgen 
Avas  well  illustrated  by  a  subject  who  had  been  tested  many  times  and 
found  to  be  one  of  the  hardiest  we  had  met  with.  One  day  he  was 
carried  in  the  low-pressure  chamber  to  an  altitude  of  22,000  feet  and 
kept  there  about  15  minutes  with  almost  no  effect  on  his  general  effi- 
ciency or  on  his  heart.  That  evening  he  dined  with  friends,  drank  a 
jnoderate  amount  of  alcohol,  and  went  to  bed  late.  The  following 
morning  he  felt  rather  giddy  and  had  a  slight  headache.  He  was 
taken  to  18,000  feet  in  the  low-pressure  chamber.  At  this  point  he 
had  reached  complete  inefficiency  by  the  psychological  tests,  was 
rather  cyanotic,  and  examination  of  his  heart  showed  the  left  border 
out  3  or  4  cm.  If  he  had  not  been  given  oxygen  at  once  or  brought 
down  quickly  he  would  have  fainted.  It  was  fortunate  for  him  that 
this  occurrence  took  place  in  the  laboratory  and  not  while  in  an  aero- 
plane thousands  of  feet  above  ground. 

We  can  only  speculate  as  to  whether  such  differences  in  condition 
are  due  to  variations  in  nervous  control  or  whether  they  have  a  basis 
in  the  chemistry  of  the  tissues.  At  any  rate,  such  temporary  lack  of 
condition  is  a  much  more  serious  matter  than  we  are  tempted  to  be- 
lieve. Athletic  trainers  recognize  it  clearly  enough  and  would  not 
allow  such  a  man  to  participate  in  a  game,  not  because  he  would  injure 
himself,  but  because  he  would  not  hold  up  to  the  strain  and  might 
lose  the  game.  In  flying,  where  the  aviator's  life  is  at  stake,  equal 
care  should  be  observed,  to  say  the  least. 


216  Ant   SERVICE  MEDICAL. 

PHYSIOLOGY  OF  EXERCISE  COMPARED  WITH  AVIATION. 

It  must  be  borne  in  mind  that  the  demiind  made  upon  the  heart  m 
aviation  is  widely  different  from  that  of  physical  exercise.  The  most 
obvious  difference  is  that  one  call  is  familiar,  and  we  are  used  to 
meeting  it ;  the  other  is  unfamiliar  and  requires  delicate  and  accurate 
reflexes  to  sense  it  and  to  meet  it  properly. 

In  the  body  at  sea  level  the  regulation  of  the  vital  functions  is 
largely  activated  by  carbon  dioxide  or,  more  broadly  speaking,  by 
the  chemical  constitution  of  the  blood.  During  exercise  a  large 
amount  of  COg  is  produced,  and  at  the  same  time  other  metabolic 
products  find  their  way  into  the  blood,  so  that  respiration  and  cir- 
culation are  stimulated  to  great  activity.  There  is  a  great  margin  of 
safety  in  this  method:  long  before  CO^  and  other  substances  in  the 
blood  have  risen  to  a  toxic  level  the  feeling  of  exhaustion  is  so  in- 
sistent that  further  physical  effort  becomes  almost  impossible.  For 
this  reason  circulatory  collapse  rarely  occurs  as  the  result  of  physical 
exertion. 

In  the  case  of  aviation,  on  the  other  hand,  no  extra  COg  is  being 
found,  and  the  low  atmospheric  pressure  so  reduces  the  partial 
pressure  of  the  COg  in  the  blood  that  it  exerts  little,  if  any,  regu- 
latory action.  The  probability  is  that  the  activation  of  the  vital 
centers  in  this  case  ceases  to  be  a  function  directly  of  the  constitution 
of  the  blood,  but  depends  on  the  oxygen  metabolism  of  the  nerve-tissue 
itself.  At  any  rate  the  margin  of  safety  between  the  stimulating  and 
the  paralyzing  effect  of  oxygen-want  is  verv  narrow,  and  since  there  is 
no  dyspnea  and  distress  preceding  the  final  collapse,  the  latter  comes 
on  with  no  Avarning ;  hence  its  terrible  danger  to  the  aviator. 

In  exercise,  again,  there  is  a  natural  check  against  excess  which  is 
lacking  in  exposure  to  rarefied  air.  When  exhaustion  comes  one  is 
forced  to  rest,  thus  terminating  the  extra  work  for  the  heart  and 
giving  a  chance  for  recovery.  In  the  case  of  the  aviator,  however, 
exhaustion  brings  exactly  the  opposite  result.  If  the  heart  falters 
for  a  moment,  not  only  do  the  nerve  centers  run  the  risk  of  exposure 
to  a  paralyzing  anoxemia,  but  the  coronary  circulation  becomes  in- 
sufficient, and  on  the  fullness  of  the  coronary  blood  supply  depends 
the  ability  of  the  heart  to  do  this  work.  Thus  a  vicious  circle  is 
started,  and,  once  the  heart  has  begun  to  fail,  nothing  can  avert 
collapse.  In  exercise  faltering  of  the  heart  means  the  opportunity  to 
recover,  in  aviation  it  means  a  break  in  competence  and  dilatation, 
and  probably  death  if  the  exposure  were  continued. 

FAINTING. 

Before  leaving  the  subject  of  fainting  it  should  be  remarked  that 
this  occurrence  is  common  at  all  altitudes,  even  the  lowest.  It  occurs, 
of  course,  in  ordinary  life  on  the  surface  of  the  earth,  not  as  a  sequel 


AIR  SERVICE  MEDICAL.  217 

of  heart  dilatation,  but  as  a  vasomotor  neurosis  pure  and  simple.  Evi- 
dently, however,  since  it  occurs  so  very  frequently  in  flying  we  can 
not  consider  it  purely  a  neurosis  or  dismiss  it  as  a  psychic  effect. 
We  must  say  rather  that  it  represents  a  demoralization  of  the  vaso- 
motor system  in  its  effort  to  make  the  fine  (even  though  not  laborious) 
adjustments  necessary  to  compensate  for  oxygen  deficiencj'. 

An  interesting  analogy  maj'  be  drawn  to  writer's  cramp  and  other 
occupational  neuroses,  which  suggests  a»  explanation  for  the  occur- 
rence of  vasomotor  phenomena,  such  as  fainting  during  exposure  to 
low  oxygen.  These  neuroses  are  never  found  on  the  long  continuance 
of  fine  muscular  movements  involving  accurate  coordination,  as  in 
writing,  use  of  the  typewriter,  sewing,  playing  a  musical  instrument, 
etc.  On  this  analogy  it  is  easy  to  understand  how  the  constant  deli- 
cate adjustments  demanded  of  the  whole  circulatory  system  during 
repeated  flights  at  ever- varying  altitudes  may  lead  to  demoralization 
of  the  vasomotor  system  even  when  the  actual  strain  is  not  great. 

P'or  this  reason  we  are  inclined  to  class  fainting  as  a  low-oxygen 
effect  even  when  it  occurs  near  the  earth.  It  is  probable  that  the 
routine  use  of  oxygen  at  the  lowest  altitudes  would  prevent  a  great 
deal  of  the  fainting  in  the  air.  As  our  work  has  progressed  we  have 
become  more  and  more  impressed  with  the  perfectly  definite  effects 
following  exposure  to  altitudes  below  5,000  feet.  These  results  are 
usualh'  not  observed  at  once,  but  are  cumulative,  and  are  ordinarily 
seen  only  in  aviators  who  have  begun  to  "  go  stale.''  It  is  not  suffi- 
cient, therefore,  to  bar  a  stale  aviator  from  high  flights;  he  should 
not  fly  at  all. 

EFFECTS  ON   PATHOLOGICAL  CASES. 

We  shall  now  consider  rapidly  the  behavior  on  low-oxygen  tests  of 
subjects  with  definite  circulatory  lesions  of  various  types. 

ARTERIOSCLEROSIS. 

Individuals  with  stiff  arteries  give  a  very  characteristic  reaction. 
They  illustrate  very  clearly  that  the  physiological  response  to  low 
oxygen  has  to  begin  at  a  very  low  altitude  in  order  to  preserve  the 
normality  of  the  body.  Such  subjects  will  show  effects  very  early, 
both  by  their  inefficiency  and  by  the  abnormality  of  their  heart 
sounds.  We  have  seen  several  who  were  "  completely  inefficient "  at 
8,000  feet,  while  at  the  same  time  the  heart  rhythm  was  hurried,  the 
first  interval  shortened,  and  the  first  sound  weak  and  valvular. 

The  essential  difficulty  with  stiff  arteries  is  that  they  will  not  play 
their  part  smoothly  in  bringing  about  increased  blood  flow  and  at 
the  same  time  sparing  the  heart.  For  this  reason,  even  in  ordinary 
life,  arteriosclerotics  must  continually  be  having  sudden  marked 
rises  in  blood  pressure,  the  result  of  every  exertion  and  every  emotion. 


218  AIK   SERVICE   MEDICAL. 

The  extra  strain  thus  thrown  on  the  heart  must  lead  either  to  over- 
work of  that  organ  or  else  to  inefficiency. 

Nothing  illustrates  so  well  this  lack  of  adaptabilitj'^  of  old  arteries 
as  aviation.  Almost  immediatel}'^  the  blood  pressure  rises  sharply. 
(We  have  observed  a  pressure  of  180  in  several  perfectly  healthy  and 
vigorous  older  men.)  At  the  same  time  the  pulse  accelerates.  This 
strain  has  to  be  carried  by  the  heart  at  a  time  when  the  coronary  ves- 
sels, themselves  sclerosed,  are  not  furnishing  the  heart  muscle  the 
extra  blood  supply  called  for,  and  the  blood  that  does  come  carries 
progressively  less  and  less  oxygen.  Of  course  the  heart  can  not  meet 
the  demand  for  more  blood  supply,  and  the  work  is  simply  not  done. 
Such  hearts  do  not  dilate,  in  our  experience,  because  they  give  up 
the  task  rather  than  overstrain  themselves;  at  any  rate,  we  have 
never  dared  to  carr}^  such  a  subject  to  a  point  where  there  was  like- 
lihood of  cardiac  dilatation. 

It  is  an  old  aphorism  that  age  means  only  the  condition  of  the 
arteries.  It  is  well  recognized  abroad  that  the  best  age  for  the  avi- 
ator is  in  the  early  twenties,  and  that  the  older  he  is  beyond  this 
point  the  less  efficient  he  is  likely  to  be  in  service.  Our  observations 
with  the  low-oxygen  tests  bear  out  this  strongly  and  suggest  that  the 
explanation  may  lie  in  slight  changes  in  the  arterial  walls  and  mus- 
culature at  a  much  earlier  age  than  it  has  been  supposed  that  such 
changes  can  occur. 

This  statement  does  not  imply  that  there  are  no  men  above  30 
or  even  in  their  forties  who  belong  to  the  "  optinmm  "  class,  but  the 
older  a  man  is  beyond  20  the  more  likely  he  is  to  show  the  arterial 
type  of  reaction  to  low  oxygen.  Thus,  many  men  of  about  35  will 
show  a  certain  hypertension  from  the  start,  with  a  constant  rise  as 
the  test  goes  on,  e.  g.,  135,  rising  to  150  to  160.  In  these  cases  the 
heart  muscle  will  carry  the  burden  much  longer  than  in  the  manifest 
arteriosclerotics,  and  there  will  be  normal  psychological  reactions 
achieved  by  heart  strain,  followed  eventually,  in  many  cases,  by  dila- 
tation of  the  heart. 

ARRHYTHMIA. 

The  effect  of  low  oxygen  on  subjects  who  have  any  tendency  to 
arrhythmia  is  very  striking.  Abnormalities  of  the  heart-beat  mech- 
anism invariably  become  exaggerated  to  an  alarming  degree.  An 
occasional  extrasystole,  for  example,  will  occur  more  and  more  fre- 
quently as  the  test  progresses,  until  the  majority  of  the  contractions 
are  of  ectopic  origin  or  until  there  are  considerable  periods  of  ab- 
normal beats  in  series  like  those  of  paroxysmal  tachycardia.  This, 
of  course,  interferes  with  the  efficiency  of  the  circulation,  so  that  these 
subjects  become  very  cyanotic,  very  uncomfortable,  and  fail  early  to 
perform  well  on  the  psj^chological  tests. 


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Type   of  case   corT.on  a'    eubj  act's   age. 
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ura.        'lo   siffii   of  exhaustion  to   a  ver>- 
high   altitude,    but   will    not  wear  well 
in   service.        "Clasr   B" 


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Tl.MK   IN  MIMTKS                                                                                                                                                ^          V 

Xo.  325. 


CADET. 


Age  22  years,   7  months. 


This  chart  shows  compensation.  There  is  a  fair  response  in  respiration.  There  is  a 
typical  rise  in  pulse  and  systolic  pressure  and  a  controlled  luit  rather  rapid  terminal 
fall  of  the  diastolic  pressure.     The  systolic  pi-essure  is  too  high  for  an  A  rating. 


89-1 


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_  1         Chart  f^l,    April    16,    'Ifc.      Irxxdintely 

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No.  63. 


CADET. 


Age  21  years,  1  month. 


Left  the  hospital  three  days  ago  where  he  was  laid  up  for  a  week  with  influenza. 
Feeling  fairly  well  to-day,  though  not  up  to  his  usual  form. 

The  first  chart  (chart  1)  is  typical  of  a  man  out  of  condition,  rather  high  systolic 
pressure,  psychic  rise  in  both  pulse  and  pressure,  followed  by  sudden  faint  at  about 
8  per  cent.  In  this  the  diastolic  pressure  fell  practically  to  zero  ;  the  systolic  pressure 
and  pulse  also  broke  sharply  as  may  be  seen  by  the  slow  recovery  after  the  experiment 
was  terminated. 

He  was  tested  again  two  weeks  later  (chart  not  given)  and  made  a  very  good  run 
with  the  exception  of  a  rather  high  blood  pressure  (148).  In  this  test  he  was  not 
completely  inefficient  when  taken  off  at  5.5  per  cent.  After  two  weeks  he  was  given 
a  third  test  (chart  2),  which  entitles  him  to  an  A  A  rating.  The  systolic  pressure 
stays  below  140,  there  is  no  break  in  diastolic,  and  there  is  a  moderate  healthy  rise 
in  pulse. 

This  case  illustrated  the  very  serious  effects  of  temporary  indisposition. 


89-3 


AIR   SERVICE    MEDICAL. 


219 


Legend  ——0,%  •111110   Pulse 

f        T  Diast.  B.  p.  Pulse  Pressure 


•--■•  Resp.  in  decil.'  per  min.  «....•  Syst  B.  P 

Accom.  in  mm.  Convergence  in  mm. 


180 

170 
1«0 
150 
UO 
130 


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nn    no     1     2    3 
TIJfB  IN  MINUTES 


No.  217.— D.  R. 


Chabt  11. 
CADET. 


25  26  2t  38   3»  SO   31   32   88 


Age  20  years,  6  months. 


There  was  a  roughening  of  the  first  heart  sound  heard  before  the  test.  No  demonstrable 
enlargement,  second  sounds  equal.  During  the  test  a  definite  systolic  murmur  developed 
and  the  pulmonic  second  sound  was  accentuated.  There  is  no  doubt  of  the  diagnosis 
of  mitral  insufficiency  well  compensated. 

The  chart  is  typical  of  most  cases  of  valvular  lesions.  The  pulse  is  high  throughout 
the  test.  The  systolic  pressure  is  high  and  uniform.  Diastolic  pressure  begins  to  fall 
between  9  and  10  per  cent,  but  is  in  control  at  all  times.  Respiration  shows  rather  a 
marked  response.  Efficiency  is  well  preserved,  the  psychological  rate  being  A.  This  is 
accomplished  at  the  expense  of  marked  overwork  of  the  heart.  Although  this  is  well 
borne  at  the  present  time,  the  presumption  is  that  the  subject  would  soon  show  the 
effects  of  wear,  and  permanent  damage  to  the  heart  might  easily  result.     Class  D. 


220 


AIB  SERVICE   MEDICAL. 


Legend 


■Oo% 
»DJa8t.  B.  p. 


•  li\tui»  Pulse  • •Reap,  in  dccil.  per  min.  • e  Syst.  B.  P 

Pulse  Pressure  Accoiu.  in  mm.  Convergence  in  mm. 


1X0 


n     n    n     o  1  2  3  4  6  8  7  8  ,8  10  It  18  13  14  15  16  17  18  19  30  21  jJ3  23  34  25  26  27  28  20\30  -SI  32  83 

tims  in  minutes 

Ohabt  12. 

No. — . — F.S.D.  CADET.  Age,  25  years  5  months. 

An  unusually  bad  record.  Systolic  pressure  very  high  and  at  the  end  rises  to  210. 
Diastolic  shows  marked  fatigue  though  the  osygen  percentage  reached  is  iiot  very  low. 
Pulse  rather  high  at  the  start  shows  very  little  acceleration  later  and  at  about  9  per  cent 
begins  to  fall  rapidly. 

The  heart  sounds  became  roughened,  suggesting  a  valvular  lesion,  which  seems  ex- 
tremely likely  from  the  blood  pressure.  Should  be  studied  further ;  test  should  be  re- 
peated.     On   the  showing  of  the   chart  given   the   rating  should   not  be  better  than   T>. 


AIB   SERVICE   MEDICAL. 


221 


Legend 


.  Diast.  B.  P. 


•  ti  II*  Pulse  m- 

Pulse  Pressure  . 


—  a  Resp.  in  decil.  per  min.  ••..«Sy»t.  B.  P 

Accom.  I'n  mm.  Convergence  in  mm. 


n     n    fi     0     1     2     3     4     6     «     7     «     9    10    11   12   18   14   15  *16   17    18  19   20   21   22   23  24  25   26   2"?   28   20   30   31   32   83 

time  in  minutes  © 

Chart  13. 


No.  163.— H.  B.  R. 


CADET. 


Age,  23  years  o  months. 


An  example  of  compensation  held  to  a  very  low  percentage  with  heavy  circulatory 
strain.  There  is  a  marked  psychic  reaction  in  both  pressure  and  pulse  at  the  start,  but 
this  subsides  somewhat  in  the  first  15  minutes  and  should  not  count  too  much  against 
the  subject.  What  is  against  him  is  the  marked  rise  in  pressure  towai'd  the  end  (106^ 
together  with  a  high  pulse  and  falling  diastolic,  which  may  be  interpreted  as  showing 
fatigue  though  no  actual  collapse  occurred.  Class  C.  Holds  his  efBciency  well  but  at 
the  expense  of  severe  heart  strain ;  high  blood  pressure  and  pulse.  Nervous  type. 
Would  wear  out  rapidly  if  used  for  high  work. 

At  the  same  time  it  may  be  remarked  that  these  very  qualities  might  make  him  a 
very  valuable  pursuit  flier  as  long  as  he  lasted. 


222 


Am  SERVICE   MEDICAL. 


Legend 


Diast.  B.  P. 


Pulse       

PuUe  Pressure 


_      Resp.  in  decil.  per  min.   ••••.>..»  Syst.  B.  P 
Accom.  in  mm.  Convergence  in  mm. 


«    "    j)     1     2     3 
TIMB  IN  MINUTES 


4  5  6 


6  9  10  11  X2  13  14  15  16  17  18  10  20  21  21   23  34  55  36  27  28  39  30  31  S3 


No.  123.— W.  B.  R. 


Chabt  14. 
CANDIDATE. 


<l> 


Age,  23  years  2  montbs. 


Suggestion  of  presystolic  thrill  and  murmur  at  apex  found  before  the  test. 

During  test  these  became  much  more  marked  and  a  systolic  murmur  developed. 
Systolic  pressure  high  from  the  start  and  steadily  increased.  Diastolic  remained  low. 
Note  the  very  marked  early  increase  in  respiration  indicating  great  discomfort  in  breath- 
ing. Became  inefficient  at  a  rather  high  oxygen  percentage.  This  chart  is  char- 
acteristic of  the  way  many  valvular  heart  cases  respond  to  the  test.  He  was  not  carried 
far  enough  to  get  the  circulatory  collapse  that  would  almost  certainly  have  come  as  a 
result  of  the  high  pressure  and  pulse.    Class  B. 


AIR    SERVICE    MEDICAL. 


223 


•  >if <■ >  > 


Reap.  Tn."dccil. '  per  mrn. 

Accom.  in  mm.l 


••     ijyst.  B.  P 
Convergence  in  mnv. 

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time  in  minutes 

Ghabt  15. 


No.  82.— D.  H.  O. 


CADET. 


Age,  24  years  7  months. 


Only  significant  finding  in  history  or  physical  examination  was  a  rather  red  throat. 
Blood  pressure  reclining  120,  standing  132,  after  exercise  146  and  two  minutes  later  138. 
Was  rather  nervous  on  test. 

Pulse  reacts  normally  but  rather  excessively  considering  the  percentage  reached.  Res- 
piration somewhat  full  from  the  start,  but  shows  no  increase.  Systolic  pressure  high 
and  steadily  increases  to  180.  At  this  point  (above  10  per  cent)  the  combination  of 
high  pressure  and  pulse  seems  to  be  more  than  the  heart  can  stand.  There  was  probably 
a  dilatation ;  at  any  rate  the  subject  almost  fainted  as  indicated  by  the  fall  in  both 
systolic  and  diastolic  pressures.  A  very  bad  run,  hardly  sufficient  to  rate  C.  The  tei-t 
was  repeated  a  week  later.  At  this  time  the  percentage  reached  was  much  lower  beforo 
inefficiency.  The  blood  pressure  was  still  a  little  too  high ;  134  rising  to  156.  On  the 
second  run  alone  he  would  be  entitled  to  B,  but  since  he  had  shown  high  blood  pressure 
twice,  very  high  once,  it  was  considered  safer  to  rate  him  C. 


224 


AIB  SERVICE   MEDICAL. 


Legenq  — ^0,%r 

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•^  Pulse 
.Pulse  Pressure 


*— j^^.'Kcsp.jin'jdecil.Tperlmin.         J^•^ -  •  •  Syst./B.  P 

■a  .      '     ^•^' '  /^ :_' 


Convergence  in  nam. 


n     n    «     0     12a 
TIME  IN  MINUTES.. 


8     9    10    11   13  13   14  15    IC   17   18    19   20    31    25    23   34  25.26  3 


S>3<»  3i  3ba7  37  Sf 


No.  382.— A.  M.  G. 


Chaet  16. 
PILOT. 


Age  25  years,  2  months. 


This  man  Is  an  instructor  in  flying  and  has  had  200  hours  of  aviation.  He  feels 
decidedly  stale  and  has  asked  to  be  relieved  of  flying  for  the  present.  Is  afraid  to  go 
up  because  he  has  such  poor  Judgment  in  his  present  condition. 

Preliminary  pulse :  Reclining  69,  standing  105 ;  after  exercise  120,  two  minutes 
later  102. 

The  only  abnormal  feature  of  his  test  was  the  slow  but  steady  decrease  In  both 
systolic  and  diastolic  pressures.  He  reached  a  fairly  low  oxygen  percentage  before 
becoming  ineflicient.  The  proof  of  staleness  here  is  not  full,  but  the  preliminary  pulse 
reactions  and   the  blood  pressures  during  the  test  are  suggestive. 


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TIMi:   IN  MINI  -I-i.^ 

No.  50. 


PILOT. 


Age  31  years,  8  months. 


In  good  health,  but  "  out  of  training,"  and  20  pounds  overweight. 

This  chart  shows  almost  total  failure  to  compensate.  There  is  very  little  change  in 
pulse  or  blood  pressure,  and  the  respiratory  reaction  is  deficient.  For  this  reason  there 
is  early  appearance  of  inefficiency  as  shown  by  the  psychological  characters,  and  he  is 
"  completely  Inefficient  "  above  9  per  cent.  Since  there  is  no  circulatory  reaction  there 
is  no  evidence  of  strain.     Class  C.     Because  inefficient  at  a  relatively  low  altitude. 


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•riMK  IN  MINI  'ITS 

-    ;:•     '-,    ::i    :i.'    :;i 

No.  144. 


CADET. 


Age  20  years,  2  months. 


Is  decidedly  "stale,"  hates  to  go  up  in  the  air  at  all.  Feels  tired  and  depressed  and 
is  discontented  in  the  service  at  present.  Certain  complications  at  home  are  on  his 
mind  a  good  deal. 

This  chart  is  typical  of  a  man  in  poor  physical  and  mental  condition.  He  fainted 
rather  suddenly  at  about  13  per  cent.  Previous  to  this  he  had  shown  little  compensatory 
response,  blood  pressure  too  low  from  the  start,  pulse  rising  slightly  and  respiration 
hardly  at  all  affected.  This  man  might  be  expected  to  faint  at  any  time  during  a 
flight  irrespective  of  elevation. 

No  rating  given  but  for  the  time  being  is  unfit  to  fly  at  all.  Withdrawn  from  flying 
and  recommendation  made  for  furlough. 


95-2 


AJCB  SEEVIOE   MEDICAX. 


225 


Legend         ■  O./^o  ^ 

r  ,     Diaat.  B.  P. 


IMimHI  Pul«e  0. 

Pulse  Pressure 


'^0  Resp.  in  decil.  per  min.       #. .^yst.  B.  P 

Accom.  in  mm.  Convergence  in  mm. 


£00 


n     »    n     0     1     2     3     4     5     6  ^1     8     9    10    11    18   13   14   15    16   17   18    10   20   31    2'i   2&  24   25   26   27   28  20   30   31    32   S3 
TIMK  tN  MINUTES 

Chabt  17. 


No.  51.— R.  N.  H. 


PILOT. 


Age  23  years,  6  months. 

This  is  another  example  of  poor  compensation.  Very  little  response  in  pulse,  none  In 
systolic  pressure,  very  low  pulse  pressure.  Respiration  increased  but  later  feel  off.  At 
the  end  there  Is  a  fall  In  systolic  and  diastolic  pressures  indicating  failure  of  the  cir- 
culatory apparatus  to  continue  even  the  limited  effort  it  is  making.  Psychological  efCects 
early.    Class  C.    Becomes  inefficient  at  a  relatively  low  altitude. 


226  AIB   SERVICE   MEDICAL. 

Sinus  arrhythmia  always  becomes  more  marked  during  the  test, 
but  is  to  be  regarded  rather  as  a  sign  of  youth  and  vigorous  reactions 
than  as  an  abnormality.  It  has  no  clinical  importance  as  far  as  we 
know. 

VALVUIiAR  DISEASE. 

The  diagnosis  of  valvular  lesions  is  easy  during  the  low -oxygen 
test.  We  have  been  able  to  identify  a  considerable  number  of  cases 
in  men  who  had  passed  rigorous  Army  examinations.  Murmurs  and 
thrills  develop  in  a  surprising  fashion  when  due  to  organic  disease. 
On  the  other  hand,  we  have  observed  a  certain  number  of  presumably 
functional  murmurs  which  did  not  alter  during  the  test  while  the 
heart  continued  to  be  perfectly  normal  in  action. 

The  behavior  of  hearts  with  valvular  lesions  depends  on  their  de- 
gree of  compensation.  If  this  is  poor  and  the  heart  muscle  weak 
they  will  give  up  the  fight  early,  allowing  inefficiency  to  develop ;  at 
the  same  time  there  will  be  marked  cyanosis  and  great  discomfort  in 
breathing,  with  palpitation.  Cases  with  poorly  compensated  mitral 
stenosis  do  especially  badly  and  are  very  uncomfortable. 

A  well-compensated  mitral  inefficiency,  however,  behaves  like  an 
overworking  normal  heart.  Such  hearts  must  have  a  good  quality  of  • 
heart  muscle  and  good  coronary  circulation  to  remain  compensated 
in  ordinary  life,  and  are  well  used  to  overworking  at  times  to  meet 
the  demands  of  every  day.  They  react  vigorously  to  low  oxygen, 
as  a  rule,  run  a  rather  high  blood  pressure,  an  increased  pulse,  give 
evidence  of  overwork  from  the  start,  and  eventually  dilate  and  give 
out. 

We  believe  that  no  man  with  a  valvular  lesion  should  be  allowed 
to  fly,  no  matter  how  perfect  the  compensation,  not  only  because  of 
the  likelihood  of  immediate  heart  strain,  with  dilatation  and  fainting, 
but  because  in  the  course  of  time  the  cumulation  of  repeated  strains 
will  bring  on  a  disastrous  condition  of  the  heart.  Cases  have  been 
observed  in  the  service  where  a  heart  originally  well  compensated 
has  eventually  broken  down,  and  the  subject  in  these  cases  is  not  only 
unfit  for  further  flying  but  the  heart  injury  may  be  irremediable  and 
he  may  have  to  look  forward  to  a  life  of  invalidism  and  early  death. 
We  have  seen  two  cases  of  mitral  disease  in  aviators  where  distress 
was  found  to  be  pretty  marked  when  the  plane  rises  to  2,500  feet. 

ATHUETIC    HEARTS. 

"Athletic  hearts "  behave  particularly  badly  under  low  oxygen. 
There  is  still  no  general  agreement  as  to  just  what  this  term  signi- 
fies, whether  it  represents  merely  a  great  hypertrophy  of  the  heart 
which  has  not  receded  or  whether  there  has  been  definite  injury  to 


AIE  SERVICE   MEDICAL.  227 

the  heart  muscle  by  strain.  The  latter  supposition  is  the  more 
probable,  because  we  know  that  the  normal  body  not  only  possesses 
great  powers  of  increasing  its  various  functions  to  meet  special  calls, 
but  that  the  recession  from  such  unusual  increase  in  tissue  and 
function  is  normally  accomplished  easily  and  safely.  We  must, 
therefore,  assume  on  general  principles  that  the  so-called  "  athletic 
heart "  means  an  injured  heart  muscle,  not  a  subinvolution.  Clin- 
ically the  diagnosis  is  usually  easy :  A  history  of  excessive  athletics, 
especially  rowing  and  distance  running,  a  heart  somewhat  enlarged 
to  percussion,  an  abnormally  heaving  apex  beat,  and  sounds  which  are 
either  notably  loud  and  booming,  or  in  a  later  stage  are  of  poor  and 
\alvular  quality.  There  is  usually  an  absence  of  murmurs,  though 
the  dilatation  can  easily  lead  to  a  relative  mitral  leak. 

The  reactions  of  the  athletic  heart  to  low  oxygen  are  always  ex- 
cessive, marked  increase  in  blood  pressure  and  pulse,  but  there  is 
likely  to  be  a  rather  early  loss  of  compensation,  since  the  damaged 
heart  muscle  is  unable  to  carry  the  strain ;  it  will  either  give  up  the 
task  (cyanosis,  inefficiency,  etc.)  or  will  dilate  and  cause  fainting. 

IV.— MANUAL  OF  OTOLOGIC  DEPARTMENT,  MEDICAL  RESEARCH 

LABORATORY. 

1.  Introductory, 
medical.  problems otologic  research  previous  to  the  war. 

Certain  unique  features  concerning  the  study  of  the  ear  in  aviation 
are  worth}'  of  special  attention.  Since  our  entrance  into  the  war 
the  Medical  Department  of  the  Aviation  Service  has  encountered  cer- 
tain problems  of  ophthalmologic,  cardio-vascular,  respiratory,  psychi- 
atric, and  other  character.  The  work  of  research  into  the  relation 
between  the  motion-perceiving  function  of  the  internal  ear  and  fly- 
ing, however,  had  been  undertaken  long  before  the  entrance  of  the 
United  States  into  the  war.  A  group  of  otologists  had  conducted 
experiments  and  carried  on  investigations  involving  the  end-organs, 
nerve  paths,  and  brain  connections  of  the  vestibular  portion  of  the 
internal  ear  for  a  period  covering  the  preceding  decade.  Many 
months  before  the  United  States  entered  into  the  conflict  several  of 
this  group  of  otologists  had  been  in  correspondence  with  the  Medical 
Department  of  the  United  States  Army  upon  the  subject  of  the 
physical  requirements  of  applicants  for  the  air  fighting  forces,  and 
the  total  available  work  done  upon  both  sides  of  the  i^tlantic  was 
made  the  basis  of  the  standards  adopted  for  these  physical  require- 
ments of  prospective  Army  fliers. 

89118—19 ^16 


228  AIE   SERVICE   MEDICAL. 

ARBITRARY   REQUIREMENTS    FIXED    BY    CHIEF   SURGEON,    AIR    MEDICAL 

SERVICE. 

Immediately  after  our  entrance  into  the  war  the  present  Air  Medi- 
cal Service  was  organized.  The  Chief  Surgeon  of  tlie  Air  Medical 
Service,  when  he  was  confronted  with  the  problem  of  formulating? 
a  plan  for  selecting  men  for  training  as  fliers  for  the  Army,  decided 
to  attempt  to  limit  the  admissions  into  this  service  to  men  who  were 
definitely  known,  as  far  as  was  possible  to  determine  by  skilled 
medical  examinations,  to  be  possessed  of  normal  physical  equipment. 

ONLY    PHYSICAL    ITEMS    COVERED    BY    MEDICAL    EXAMINATION. 

The  determination  of  their  possession  of  all  attributes  other  than 
physical  fell  to  another  division  of  the  Air  Service,  the  Mental 
Examining  Board,  and  at  no  time  constituted  a  part  of  the  work  of 
the  Medical  Service.  The  sole  duty  of  the  Chief  Surgeon  with  respect 
to  the  examination  of  applicants  for  flying  training  was  to  demon- 
strate in  each  man  the  presence  of  normal  physical  equipment. 

FORMATION   OF   STANDARD   BLANK   FOR  PHYSICAL  EXAMINATION. 

F|0r  the  purpose  of  furnishing  a  standard  plan  on  which  these 
physical  examinations  could  be  conducted  upon  a  uniform  basis, 
blank  609,  A.  G.  O.,  was  formulated,  after  consultation  with  the  high- 
est medical  authorities  in  the  various  special  fields  of  medical  work 
covering  the  complete  physical  examination  of  man.  The  ophthal- 
mologist, the  otologist,  the  rhinolaryngologist,  the  neurologist,  the 
respiratory  and  cardiovascular  specialist,  the  gastroenterologist,  tne 
orthopaedist,  the  general  surgeon,  the  dermatologist,  the  genito- 
urinary specialist,  are  all  represented  in  the  constitution  of  this 
examination  blank,  and  the  general  field  of  complete  physical  exami- 
nation covered  to  the  satisfaction  of  each. 

PHYSICAL  EXAMINING   UNITS. 

Special  care  was  exercised  to  pick  the  highest  grade  medical  exami- 
ners available  at  each  point  where  it  was  deemed  necessary  to  estab- 
lish a  Physical  Examining  Unit,  and  the  work  of  each  unit  was  de- 
partmentalized in  the  best  manner  possible  to  render  each  examiner 
capable  of  serving  in  his  most  efficient  capacity. 

No  difficulty  was  encountered  in  securing  the  services  of  men  well 
trained  in  all  special  medical  work  represented  in  this  blank,  with 
the  notable  exception  of  the  examination  of  the  internal  ear.  This 
was  relatively  so  new  that  the  limited  number  of  those  capable  of 
doing  this  portion  of  the  work  rendered  it  necessary  in  establishing 
each  Physical  Examining  Unit,  to  pay  special  attention  to  the  selec- 
tion of  the  otologist.    In  manj'  instances  it  was  necessary  to  develop 


AIE  SERVICE   MEDICAL.  229 

the  man  capable  of  handling  this  portion  of  the  work  by  a  special 
intensive  course  of  training  and  instruction. 

DETAILED  INSTRUCTIONS. 

Carefully  detailed  instructions  were  prepared  by  high  authorities 
upon  the  individual  medical  branches  involved  in  this  special  ex- 
amination, and  these  were  sent  to  each  Physical  Examining  Unit  for 
its  guidance;  from  time  to  time  additional  instructions  were  issued 
by  the  Chief  Surgeon  for  the  purpose  of  further  improving  the  ex- 
amining service ;  special  visits  to  Physical  Examining  Units  were  made 
from  time  to  time  with  a  view  to  maintaining  this  service  at  its  high- 
est efficiency,  and  frequent  consultation  of  the  best-informed  medical 
authorities  on  the  subjects  involved  were  held,  in  attempts  to  omit 
nothing  which  might  improve  the  quality  of  this  work.  Full  ref- 
erence was  made  to  the  accumulated  experience  of  the  Allies;  and 
confidential  and  other  reports  from  medical  officers  in  England  and 
France  were  thoroughly  digested  and  used  to  shape  up  the  service  of 
the  Chief  Surgeon's  examiners. 

IMPORTANT  SENSORY  EQUIPMENT. 

Among  the  applicant's  sensory  equipments  which  were  deemed  im- 
portant to  demonstrate  as  normal  were  visual  perception,  sound  per- 
ception, deep  sensibility  (or  muscle- joint-splanchnic  or  kina3sthetic 
sense),  tactile  sense,  and  motion  perception;  special  examination  of 
olfactory,  taste,  and  certain  other  special  senses,  such  as  cold,  heat, 
pain,  pleasure,  sexual,  tickle,  hunger,  thirst,  nausea,  and  others  were 
not  deemed  of  sufficient  military  importance  to  warrant  special 
scrutiny. 

COMPARISON  or  GROUND  AND  AIR  SERVICE  CONDITIONS. MOTOR  COORDINA- 
TIONS.  BODILY     ADJUSTMENTS. — IMPORTANCE     OF     SENSES     TO     MOTOR 

ACTS. 

The  difference  between  the  man  on  the  ground  and  the  man  in  the 
air  lies  in  the  fact  that  the  former  can  stand  still,  the  latter  can  not. 
When  the  flier  walks  across  the  field  to  his  plane,  all  his  motor  co- 
ordinations are  concerned  with  maintaining  the  proper  relation  be- 
tween his  body  and  the  element  which  is  supporting  its  weight,  the 
earth.  When  he  straps  himself  in  the  seat  before  flight  he  practically 
straps  wings  to  his  body;  thenceforth,  until  the  end  of  his  flight, 
everj^  motor  coordination  is  concerned  with  maintaining  a  proper 
relation  with  the  new  element  which  is  supporting  his  weight,  the 
air.  The  only  means  he  possesses  of  adjusting  his  relation  with  the 
new  weight-supporting  element  is  the  plane;  while  flying,  all  motor 
coordinations,   whether   carefully    calculated    or    instinctively    per- 


230  AIK  SERVICE   MEDICAL. 

formed,  are  concerned  exclusively  with  controlling  the  plane.  The 
promptness  and  efficiency  with  which  motor  coordinations  are  per- 
formed depend  directly  upon  the  acuteness  of  sensory  perceptions. 

MOTION    INDISPENSABLE    TO    FLYING. — SPECIAL    IMPORTANCE    OF    MOTION 
SENSING. — INTEGRAL  ELEMENTS  IN   MOTION  SENSING. 

Rising  in  the  air  in  an  aeroplane  is  made  possible  only  by  rapid 
motion.  Acuity  of  motion  perception  assumes  much  greater  impor- 
tance to  the  flier  than  to  the  pedestrian,  and  in  order  to  appreciate 
the  full  importance  of  this,  one  must  have  a  clear  conception  of  the 
component  senses  going  to  make  up  motion  perception.  Muscle-and- 
joint  sense,  splanchnic,  visceral  sense,  kinajsthetic  sense — all  grouped 
for  convenience  under  the  term  "  deep  sensibility,"  vestibular  sense, 
vision  and  tactile  sense,  each  participate  in  the  composite  of  gen- 
eral motion  perception. 

DEEP  SENSIBILITY  ON  THE  GROUND  COMPARED  WITH  IN   AIRPLANE. 

The  motion  sensing  of  deep  sensibility  on  the  ground  is  practically 
exclusivelj^  concerned  with  sensing  the  effect  of  the  pull  of  gravity 
upon  the  bod.y ;  in  the  air  it  is  also  concerned  with  sensing  the  effect 
upon  the  body  of  two  other  pulls,  that  of  the  plane's  propeller  and 
that  of  centrifugal  force  on  curves.  Impulses  generated  by  these 
three  pulls  coming  in  via  the  deep  sensibility  tract  must  undergo 
accurate  analysis  in  the  brain  and  be  properly  estimated  and  labeled, 
if  confusion  and  misinterpretation  are  to  be  avoided.  While 
such  analysis  is  accomplished  by  normal  individuals,  it  is  only  at 
the  expense  of  a  certain  amount  of  the  more  accurate  sensing  of  the 
pull  of  gravity.  Whereas  on  the  ground  practicall}'  100  per  cent  of 
this  incoming  information  expresses  gravity  pull,  a  less  percentage 
of  gravity  pull  is  expressed  by  it  in  the  air. 

VISION  ON  THE  GROUND  COMPARED  WITH  IN  THE  AIR. 

Vision,  possibly  the  most  important  of  all  motion-perceiving  senses 
on  the  ground,  suffers  some  impairment  of  its  usefulness  in  the  air 
by  reason  of  the  reduction  in  the  number  of  visible  elements  in  the 
new  environment,  such  as  the  usual  objects  making  up  the  landscape. 
When  darkness  or  cloud  further  reduces  the  utility  of  vision,  this 
sense  becomes  almost  eliminated  as  a  source  of  guiding  information 
to  the  flier. 

TACTILE  SENSE  RELATIVELY  UNIMPORTANT. 

Tactile  sense  contributes  less  than  any  of  the  other  three  senses 
to  motion  perception  on  the  ground ;  to  the  flier,  although  insulated 
by  warm  clothing,  goggles,  gauntlets,  and  helmet,  it  is  still  of  value 
as  a  source  of  guiding  information. 


AIR  SERVICE   MEDICAL.  231 

VESTIBULAR  SENSE,  ITS  MOTION  SENSING  UTILITY  AS  GREAT  IN  THE  AIR  AS 

ON  THE  GROUND. 

Vestibular  sense  sutfers  no  depreciation  in  utility  in  the  air  as 
compared  with  on  the  ground.  Its  sole  function  has  always  been, 
and  continues  unaltered  in  any  way  to  be,  pure  sensing  of  motion. 
In  flying,  therefore,  its  function  assumes  a  relatively  greater  impor- 
tance than  that  of  the  other  special  senses  cooperating  with  it  to 
furnish  the  individual  with  his  composite  of  knowledge  concerning 
motion. 

In  view  of  the  foregoing,  it  is  apparent  that,  in  flying,  motion  takes 
on  a  much  greater  importance  as  regards  potential  safety  or  disaster 
for  the  individual  than  it  possesses  on  the  ground  and  that  motion 
perception  is  commensurately  of  greater  importance  in  the  air  than 
on  the  ground. 

Eegardless  of  the  actual  percentages  which  would  express  the  shares 
of  vision,  deep  sensibility,  vestibular  and  tactile  sense  in  the  total  of 
motion-sensing  on  the  ground,  it  is  established  that  three  of  these  four 
are  reduced  in  efficiency  by  conditions  incidental  to  flying,  and  the 
fourth,  vestibular  sense,  is  not  so  reduced,  and  is  therefore  of  rela- 
tively increased  importance.  It  follows  that  it  is  of  prime  impor- 
tance to  determine  that  men  to  be  trained  as  fliers-  possess  normal 
vestibular  apparatus.  So  important  is  it  for  the  flier  to  possess  nor- 
mal vestibular  acuity  of  motion-perception  that  no  man  should  be  per- 
mitted to  begin  training  as  a  pilot  who  has  not  definitely  shown  nor- 
mal reactions  to  vestibular  tests. 

VESTIBULAR  FUNCTION  STANDARD  REQUIREMENTS. 

The  entire  vestibular  apparatus  was  tested  as  carefully  and  as 
accurately  as  the  state  of  our  knowledge  concerning  it  permitted.  It 
was  decided  to  reject  applicants  whose  vestibular  apparatus  gave  evi- 
dence of  motion-sensing  acuity  below  a  certain  degree,  albeit  it  was 
fully  realized,  in  establishing  this  limit,  that  it  in  no  way  represented 
a  line  of  demarkation  between  acuities  of  this  perception  compatible 
with  and  incompatible  with  flying. 

POSSIBILITIES  OF  GREATER  LATITUDE  REALIZED. 

It  was  fully  realized  hj  the  Chief  Surgeon  and  his  staff  that  it  is 
possible  for  a  man  to  fly  with  a  vision  of  20/40  or  20/60,  or  with  a 
talipes,  or  with  a  hearing  of  5/40.  The  decision  was  arbitrarily  made, 
however,  that  no  man  would  be  accepted  for  flying  training  by  the 
Army  except  those  with  20/20  vision,  absence  of  gross  malformations, 
40/40  hearing,  and  acuity  of  vestibular  motion-perception  as  repre- 
sented by  a  minimum  of  16  seconds'  nystagmus  and  normal  past- 
pointing  and  falling  responses  to  standard  stimulation. 


232  AIR  SERVICE   MEDICAL. 

DIFFICULTIES   IN   DECIDING  UPON   ARBITRARY  STANDARDS CONFIRMATION 

OF  WISDOM   OF   ADOPTED   STANDARDS. 

At  the  time  of  the  establishment  of  these  standards  it  was  recog- 
nized as  a  very  difficult  matter  to  state  dogmatically  what  consti- 
tuted the  average  length  of  nystagmus  and  past-pointing.  All  that 
could  be  relied  upon  were  deductions  from  clinical  experiments 
with  a  series  of  healthy  individuals  examined  by  various  observers 
over  a  period  covering  over  10  years  as  contrasted  with  the  impaired 
responses  observed  in  over  a  thousand  pathologic  cases.  It  was 
realized  that  it  was  a  great  responsibility  to  establish  what  should 
be  regarded  as  normal  responses.  It  is  therefore  with  a  great  deal 
of  satisfaction  that  we  publish  at  this  point  the  composite  results  of 
the  turning-chair  test  performed  by  skilled  standardized  otologists 
in  the  examining  units  on  many  tens  of  thousands  of  applicants  for 
the  Aviation  Service.  A  compilation  of  statistics  has  been  made, 
the  digest  of  which,  with  respect  to  responses  in  nystagmus,  past- 
pointing  and  falling,  entirely  confirms  the  judgment  upon  which 
the  original  standards  were  based. 

The  turning-chair  tests  proper,  exclusive  of  the  static  and  dynamic 
tests,  are  cause  for  practically  all  of  the  rejections  in  this  particular 
field,  being  2  per  cent  out  of  a  total  of  2.04  per  cent,  or  2  out  of 
every  100  men  examined.  The  average  duration  of  nystagmus  of 
the  entire  number  of  men  examined  was,  after  turning  to  the  right. 
23.5  seconds;  after  turning  to  the  left,  23.2  seconds.  In  those  who 
qualified,  the  nystagmus,  after  turning  to  the  right  was  23  seconds, 
after  turning  to  the  left,  23.1  seconds. 

The  average  number  of  past-pointings  for  the  total  number  ex- 
amined is  as  follows : 

After  turning  to  right  with  right  arm 3.  8  times 

After  turning  to  right  with  left  arm 3.  7  times 

After  turning  to  left  with  right  arm 3.  8  times 

After  turning  to  left  with  left  arm 3.  7  times 

POSSIBILITY  OF  ALTERATION  IN  ADOPTED  STANDARDS. 

The  Chief  Surgeon  held  himself  in  readiness  to  alter  the  adopted 
physical  standards  at  any  time  evidence  indicating  the  wisdom  of 
so  doing  was  adduced;  realizing  the  wejjilth  of  available  material 
for  Army  fliers  at  the  start  of  the  formation  of  the  United  States 
Flying  Corps,  it  was  deemed  best  to  maintain  the  highest  standards 
until  it  became  apparent  that  a  change  was  for  the  best  interests  of 
the  service. 

FALLIBILITY  OF  ENTRANCE  EXAMINING   SERVICE. 

The  physical  examinations  of  applicants  were  carried  out  at  67 
Physical  Examining  Units,  82  of  which  wpvp  oonstitnted  by  Army 


AIR   SERVICE   MEDICAL.  233 

medical  men  in  various  camps.  As  was  to  be  expected,  a  certain 
amount  of  evidence  of  the  fallibility  of  these  examinations  has  come 
to  light.  Certain  men  have  been  encountered  in  the  Air  Service  who 
were  physically  unfit,  and  certain  others  have  been  rejected  who 
were  physically  fit.  Considering  the  magnitude  of  the  task,  how- 
ever, a  review  of  the  results  of  the  examinations  of  a  hundred  thou- 
sand applicants  in  nine  months  reveals  a  performance  on  the  part 
of  these  examining  units  which  is  satisfadtory  to  the  Chief  Surgeon. 

2.  Ear,  Nose  and  Throat  Kequirements. 

details  regarding  examination  of  questions  of  blank  609,  a.  g.  o., 
from  13  to  21,  not  including  20,  which  has  already  been  touched 

UPON. 

13.  History  of  ear  trouble — 

{a)  Ever  have  ringing  or  buzzing  in  either  ear,  earache,  dis- 
charge, or  mastoiditis  ? 
(6)  Ever  have  attacks  of  dizziness  from  any  cause? 
(c)  Ever  been  seasick ?     If  so,  how  often  and  how  long  does  it 

last? 
{d)  Ever  had  a  severe  injury  to  head? 

The  answers  to  question  13  are  merely  designed  in  a  general  way  to 
arrive  at  an  indication  of  any  previous  ear  trouble.  It  is  to  be  taken 
into  consideration  that  very  few  candidates  are  willing  to  admit  the 
history  of  ear  discharge  or  dizziness,  and  conclusions  will  have  to  be 
drawn  from  the  examination  0*1'  the  drumhead  and  subsequent  hearing 
and  rotation  tests. 

It  is  the  universal  experience  that  all  candidates  deny  that  they 
have  ever  been  seasick,  thinking  thereby  to  prove  that  they  would  be 
unaffected  by  the  motion  of  an  aeroplane.  Answers  to  this  question 
for  that  reason  must  be  taken  with  considerable  allowance.  It  is  to 
be  emphasized  that  it  would  be  improbable  for  a  person  with  per- 
fectly normal  ears  not  to  become  seasick  upon  his  first  exposure  to  a 
rough  sea. 

14b.  A'pyeavaiu.e  of  memhraua  tympam. — A  jjerf oration  of  the 
drumhead,  unless  transitory,  is  to  be  regarded  as  a  cause  for  rejection. 
If  the  drumhead  is  excessively  thin  and  scarred,  even  if  the  hearing  is 
normal,  the  applicant  should  be  rejected.  Experience  has  shown  that 
even  in  the  low-pressure  chamber  of  the  laboratory  perforations  can 
easily  occur  in  such  drums  by  a  rapid  descent. 

Pathological  conditions  of  the  internal  ear  disqualify.  Acute  or 
chronic  disease  of  the  middle  ear  disqualifies,  except  that  reexamina- 
tion after  full  recovery  may  be  made  the  basis  of  subsequent  accep- 
tance. Moderately  retracted  drumhead,  loss  of  light  reflexes, 
thickened  drum  membrane,  and  chplk  deposits  do  not  disqualify  pro- 


234  AIR  SERVICE   MEDICAL. 

vided  the  hearing  is  normal.  The  pathology  of  the  drumhead  is  not 
an  index  of  the  hearing  ability.  No  conclusions  can  be  drawn  without 
liearing  tests. 

15  to  18.  Nasopharynx. — This  region  must  be  carefully  examined. 
If  defect  can  be  removed  by  operation,  this  should  be  required  prior 
to  acceptance.  If  nonoperable  or  operation  is  refused,  it  is  a  cause 
for  rejection. 

The  question  as  to  what  degree  of  deviation  of  the  septum  demands 
an  operation  is  a  difficult  one  to  answer  and  must  be  left  to  the  ex- 
perience of  the  examiner.  One  thing  must  always  be  clearly  borne 
in  mind;  aside  from  the  straightening  of  an  occlusive  deviation  for 
the  purpose  of  giving  the  candidate  better  air,  resecting  the  septum  is 
not  infrequently  of  great  value  as  a  prophylactic  measure.  .  The  ma- 
jority of  individuals  who  have  trouble  with  their  ears  are  troubled 
because  of  a  postnasal  and  Eustachian  tube  catarrh.  Septal  devia- 
tion far  back,  impinging  on  the  inferior  turbinate  and  acting  as  a 
continual  irritant  to  the  nasopharynx,  should  be  corrected.  Cases 
of  marked  deviation  which  have  led  to  atrophic  condition  of  the 
mucus  membranes  do  not  necessarily  require  operations.  The  prime 
object  is  to  prevent  acute  postnasal  trouble  which  might  come  on  as 
a  result  of  exposure,  rather  than  to  attempt  to  obviate  an  insidious 
middle-ear  catarrh  which  might  have  come  on  in  later  life. 

The  nares  should  be  most  carefully  examined  for  any  signs  of  acces- 
sory sinus  diseases.  Even  a  suspicion  of  this  condition  should  lead 
to  a  most  careful  and  painstairing  examination,  including  properly 
taken  X-ray  stereoscopic  photographs. 

16.  Condition  of  tonsils  and  history  of  attacks  of  tonsillitis. — The 
diagnosis  of  diseased  tonsils  is  a  difficult  one  and  must  be  left  largely 
to  the  experience  of  the  individual  examiner.  Candidates  are  disin- 
clined to  admit  a  history  of  sore  throats.  It  must  not  be  forgotten 
that  probably  80  per  cent  of  the  sick  calls  on  the  other  side  is  made 
up  of  sore  throats.  Soldiers  who  never  complain  of  throat  trouble 
in  this  country  when  they  are  subjected  to  the  exposures  incidental 
to  field  service  rapidly  develop  inflammatory  throat  conditions,  which 
disqualify  temporarily  for  duty.  One  should  be  cautious  in  declaring 
a  tonsil  healthy.  All  throats  should  be  examined  under  good  illumi- 
nation ;  attempt  to  express  contents  of  crypts  should  be  made,  and  if 
questionable  matter  can  be  squeezed  out  the  tonsils  should  be  removed. 
Buried  tonsils  in  which  the  anterior  pillar  is  affected  should  be  re- 
moved, as  should  the  hypertrophic  type.  The  experience  in  this  lab- 
oratory has  been  that  in  spite  of  the  fact  that  all  candidates  were 
originallj'^  examined  by  throat  specialists,  many  when  reexamined  in 
this  institution  showed  diseased  tonsils.  Our  general  impression  is 
that  it  is  better  to  err  slightly  on  the  side  of  radicalism  in  regard  to 
operation  on  the  tonsils  for  those  about  to  enter  active  military  service. 


AIR  SERVICE   MEDICAL.  235 

Examination  of  the  teeth  must  not  be  neglected.  It  must  never  be 
forgotten  that  crowned  teeth,  pyorrhea,  and  alveolar  infections  may 
be  the  sources  of  much  toxemia.  Special  attention  should  be  given 
to  this  matter,  and  if  there  is  any  doubt  in  the  mind  of  the  examiner 
as  to  the  condition  of  the  candidate's  teeth  he  should  be  instructed  to 
have  his  mouth  put  in  good  shape  before  finally  passing  him. 

17.  Adenoid  tissue  is  very  common  in  children  and  increases  in  size 
from  birth  to  the  age  of  6  years  and  then  normally  subsides  about  the 
age  of  puberty.  One  does  not  expect  to  find  much  adenoid  tissue  in 
adults.  Adenoids  do  their  harm  early  in  life,  and  this,  as  far  as  it 
concerns  this  examination,  is  evidenced  by  deformed  jaws,  misshapen 
noses,  and  poor  hearing.  Adenoid  tissue  in  the  adult  is  easily  seen 
Avith  a  post-nasal  mirror,  the  digital  examination  being  unnecessary. 

18.  The  condition  of  the  Eustachian  tubes  is  one  of  vital-importance. 
Generally  speaking,  it  can  be  said  that  if  the  candidate's  drumhead 
and  hearing  are  normal  the  Eustachian  tube  is  probably  in  good  con- 
dition. In  addition,  regulations  require  that  the  patulence  of  the  tube 
should  be  demonstrated  by  the  auscultation  tube  during  inflation  by 
means  of  Politzerization  or  catheterization.  The  former  procedure 
is  ample  for  all  practical  purposes.  If  tubal  troubles  are  of  such  a 
nature  as  to  demand  it,  an  examination  should  be  made  with  some 
good  pharyngoscope. 

STIMULATION    OF    END-OKGANS. — RESULTS    SENSORY,    MOTOR. — VERTIGO. — 
KIND  OF  MOTION  USED  AS  STIMULUS. 

20.  Vestibular  tests. — The  motion-perceiving  apparatus  of  the  in- 
ternal ear  is  subjected  to  stimulation  by  motion  of  certain  standard 
quantity  and  quality,  and  the  results  are  observed  according  to  uni- 
form standard  methods.  Two  results  are  noted — a  sensory  result,  the 
subjective  sensation  of  motion,  and  a  motor  result,  involuntary  move- 
ment of  the  eyes.  When  the  subjective  sensation  of  motion  is  in 
accord  with  fact,  we  call  it  normal  sensing  of  motion ;  when  it  is  not 
in  accord  with  fact,  we  call  it  "vertigo."  The  only  difference  be- 
tween normal  perception  and  vertigo  lies,  in  the  sensing  of  motion 
being  in  accord  with  or  contrary  to  fact.  The  most  practical  means 
of  applying  motion  stimulus  is  by  the  rotating  chair,  inasmuch  as 
the  application  of  motion  in  a  linear  direction,  for  the  period  of 
time,  and  in  the  intensity  necessary  to  elicit  certain  standard  responses 
to  that  stimulus  would  necessitate  apparatus  entirely  too  bulky  to 
be  susceptible  of  practical  application  under  ordinary  conditions  of 
office  examination.  By  making  use  of  a  rotational-motion  stimulus 
instead  of  a  linear-motion  stimulus  it  was  possible  to  work  out  a 
standard  means  of  applying  motion  stimulus  in  certain  definite  qual- 
ity and  quantity  in  a  manner  and  by  means  of  an  apparatus  easily 
handled  in  an  office.    For  this  reason  only  the  subject  of  the  tests  of 


236  AIE   SERVICE   MEDICAL. 

the  vestibular  apparatus  is  made  to  experience  rotational  vertigo. 
An  additional  advantage  in  using  the  rotating  chair  is  that  it  applies 
motion  stimulus  of  a  character  to  produce  a  more  enduring  stimula- 
tion of  the  end-organs  of  the  semicircular  canals. 

Motion  in  a  linear  direction  applied  to  a  fluid  contained  in  a  closed 
semicircular  canal  is  physically  incapable  of  setting  up  a  flow  of  that 
fluid,  just  as  rotational  motion  applied  to  a  fluid  contained  in  a 
straight  canal  can  not  set  up  a  flow. 

NYSTAGMUS. 

Ewald's  experiment  long  ago  determined  that  involuntary  pulling 
of  the  eyes  in  a  certain  definite  direction  and  plane  occurs  during 
the  time  the  fluid  in  a  normal  semicircular  canal  is  made  to  flow 
in  one  direction ;  and  during  the  time  this  fluid  is  made  to  flow  in  the 
opposite  direction  involuntary  pulling  of  the  eyes  in  the  opposite 
direction  occurs.  By  applying  rotational  motion  it  is  possible  to  re- 
produce Ewald's  experiment  in  effect,  as  a  test  of  eye  reactions  to 
vestibular  stimulation;  and  when  the  character  and  intensity  of 
rotational  stimulus  is  standardized,  comparisons  of  the  results  can  be 
made  and  a  normal  eye  reaction  determined.  This  motor  expression 
of  motion  stimulation  is  nystagmus. 

MEASURING      VEKTIGO VOLUNTARY      TESTIMONY INVOLUNTARY      TESTI- 
MONY  TECHNIQUE POINTING        TEST STANDARD       TECHNIQUE         OF 

POINTING  TESTS. 

The  normal  man  experiences  a  sensation  of  vertigo  for  between 
15  and  40  seconds  after  being  turned  according  to  standard  tech- 
nique. Evidence  of  this  subjective  sensation  may  be  had  by  volun- 
tary or  involuntary  testimony ;  voluntary  testimony,  such  as  "  I'm 
turning  to  the  right,"  "I'm  still  turning  to  the  right,"  etc.,  during 
the  persistence  of  the  subjective  sensation;  involuntary  testimony, 
such  as  pointing  test  and  falling.  Standard  tests  make  use  of  invol- 
untary testimony  in  all  cases;  occasionally  this  is  amplified  by  vol- 
untary testimony  with  advantage.  In  observing  the  pointing  before 
turning,  a  very  important  element  in  the  test  can  be  injected  by  im- 
planting in  the  mind  of  the  applicant  the  definite  idea  that  he  is  to 
attempt  to  determine  the  location  in  space  of  the  observer's  finger 
solely  by  registering  in  his  memory  the  location  of  it  according  to 
his  tactile  sense.  This  can  be  augmented  by  having  him  touch  the 
observer's  finger  in  more  than  one  position,  as,  for  instance,  directly 
in  front  of  the  right  hand,  come  back  and  touch;  then  locate  again 
30  degrees  outward  and  come  back  and  touch;  the  same  procedure 
in  front  of  the  left  hand.  This  implants  in  his  mind  the  funda- 
mputal  iden  of  being  able  to  oT'ientate  himself  solely  by  means  of  in- 


AIR   SERVICE   MEDICAL.  237 

formation  coming  from  his  tactile,  end-organs.  After  standard  rota- 
tion to  the  right,  for  example,  normal  man  experiences  a  certain  very 
definite  vertigo,  a  subjective  sensation  of  turning  to  the  left  in  the 
same  plane  as  the  rotation  for  a  normal  period  of  time.  If  the  point- 
ing test  is  carried  out  during  this  period  of  vertigo,  instead  of  suc- 
ceeding in  pointing  accurately  to  the  testing  finger  he  executes  the 
pointing  in  accordance  with  his  subjective, sensation  of  motion.  Feel- 
ing that  he  is  turning  definitely  away  from  the  testing  finger  to  the 
left,  for  example,  he  reaches  for  it  to  the  right.  This  is  normal  past- 
pointing. 

INSULATION  OF  SUBJECT. 

The  insulation  of  the  applicant  during  this  test  should  be  as  per- 
fect as  possible.  A  black  domino  mask  should  be  used,  absolute 
quiet  should  be  maintained,  olfactory  impressions  should  be  shunted 
out,  and  he  should  be  left  as  solely  as  possible  dependent  upon  the 
information  brought  to  him  along  the  vestibular  tract  alone. 

SIGNALING  SUBJECT — OBVIATING  SEARCH    MOVEMENTS — OBSERVING   PAST- 
POINTING — HOW  TO  CONSTRUE  COMPENSATORY  POINTING. 

The  applicant  should  be  definitely  instructed  before  turning  that 
he  should  not  expect  a  verbal  order  to  touch  the  observer's  finger, 
raise  his  hand  and  come  back,  and  attempt  to  find  it  after  the  turn- 
ing; he  should  be  practiced  before  turning  in  executing  his  touch, 
raising  his  hand,  and  coming  back  to  find  the  finger  upon  receipt  of 
the  signal  from  the  observer's  finger  as  it  comes  into  the  position 
which  it  maintains  during  the  test — the  observer  bringing  up  his 
finger  into  position  so  as  to  tap  the  applicant's  finger  as  a  signal  foi- 
him  to  execute  his  pointing  without  verbal  command.  It  is  very 
important  for  the  applicant's  finger  to  find  a  finger  of  the  observer 
when  he  comes  down  in  search  of  the  finger  which  is  testing  him. 
Otherwise,  there  is  injected  into  his  mind  a  disconcerting  element  of 
dissatisfaction  in  having  failed  to  find  the  finger  for  which  he  was 
searching.  For  this  purpose  the  index  finger  of  the  observer's  left 
hand  can  be  held  in  readiness  to  furnish  the  touch  necessary  to  shunt 
out  this  sense  of  failure.  In  observing  the  past-pointing  after  rota- 
tion, the  observer's  right  index  finger  should  be  definitely  fixed 
against  the  observer's  hip-  so  that  visual  attention  to  it  on  the  part  of 
the  observer  can  be  dispensed  with,  the  hip  rest  insuring  its  remain- 
ing definitely  where  it  was  when  the  applicant  first  touched  it  in 
making  the  pointing  test.  The  observer's  eyes  can  be  free  to  watch 
the  applicant's  finger  at  the  top  of  the  swing.  Past-pointing  at  the 
top  of  the  swing  is  just  as  definitely  normal  past-pointing  as  at  the 
completion  of  return  to  touch.  Many  cases  compensate  after  evincing 
a  normal  tendency,  let  us  say,  to  past-point  outward  with  the  right 
hand  when  they  should  do  so,  and  subsequently  execute  a  compensa- 


238  AIE   SERVICE   MEDICAL. 

tory  touch  or  inward  pointing  at  the  bottom  of  the  return.  In  such 
cases  the  pointing  should  be  registered  as  that  executed  at  the  top  of 
the  swing,  which  is  the  primary  and  clean  response  before  it  has  been 
altered  by  the  subconscious  or  conscious  compensation  effected  by 
other  mental  processes.  Visual  attention  on  the  part  of  the  observer 
to  the  applicant's  hand  at  the  beginning  of  his  downward  pointing 
is  of  enormous  importance  and  it  should  be  very  carefully  observed 
as  part  of  the  standard  technique. 

FALL  TEST. 

The  fall  test  is  similar.  A  normal  man,  on  attempting  to  sit  up- 
right after  leaning  forward  during  right  rotation,  feels  that  he  is 
turning  to  the  left,  for  instance,  and  so  gives  involuntary  expression 
to  this  sensation  by  falling  to  the  right  on  attempting  to  assume  an 
erect  sitting  posture. 

These  tests  can  be  completed  in  less  than  five  minutes.  Inci- 
dentallv,  these  tests  are  in  no  sense  severe  and  are  in  fact  seldom 
regarded  even  as  unpleasant. 

Occasionally  nausea  occurs  after  these  turnings;  it  is  then  merely 
necessary  to  stop  the  examination  for  the  time  being  and  to  com- 
plete the  remainder  of  the  tests  after  an  interval  of  half  hour. 
There  is  no  need  whatever  to  make  these  tests  in  any  way  distressing 
to  the  candidate. 

OBVIOUSLY  UNFIT  CASES — BORDEK-LINE  CASES — CALORIC  TEST — DETAILS — 
ALLOWABLE  LATITUDE — DRUMHEAD   INSPECTION. 

With  respect  to  the  internal  ear  motion-sensing  apparatus,  its 
nerve  paths  and  brain  connections,  these  turning  tests  quickly  sepa- 
rate the  obviously  fit  from  the  unfit.  The  majority  of  the  candidates 
show  normal  responses;  no  further  testing  is  required,  and  they 
therefore  qualify  and  are  accepted.  Some  candidates  show  such 
markedly  subnormal  responses  that  they  are  immediately  disqualified 
and  rejected.  A  limited  number  give  what  might  be  termed 
"border-line"  responses;  the  question  then  arises,  Has  this  particu- 
lar applicant  sufficient  motion-sense  to  become  an  aviator?  It  is 
here  that  the  caloric  test  is  useful.  The  turning  has  tested  both  the 
right  and  left  ears  simultaneously.  The  caloric  method  enables  us 
to  test  each  ear  separately.  Water  at  68°  F.  is  allowed  to  run  into 
the  external  auditory  canal  from  a  height  of  about  3  feet  through  a 
stop  nozzle,  with  the  head  tilted  30°  forward,  until  the  eyes  are 
seen  to  jerk  and  the  individual  becomes  dizzy.  The  length  of  time 
from  the  beginning  of  the  douching  until  the  jerking  of  the  eyes 
becomes  apparent,  or  until  the  applicant  says  he  is  dizzy,  is  accu- 
rately measured  by  a  stop-watch.  The  type  of  nystagmus  is  then 
noted.     With  head  in  upright  position,  it  should  be  rotary  and  the 


\ 

AIR   SERVICE   MEDICAL.  239 

direction  of  the  jerk  should  be  to  the  side  opposite  the  ear  douched. 
The  length  of  the  douching  shown  by  the  stop-watch  in  the  normal 
is  40  seconds.  The  eyes  are  then  closed  and  the  past-pointing  is 
taken.  The  head  is  then  immediately  inclined  backward  60°  from 
the  perpendicular  (or  90°  from  the  original  position).  There  should 
then  appear  a  horizontal  nystagmus  to  the  side  opposite  to  the  ear 
douched.  The  eyes  are  then  closed  and  the  past-pointing  is  taken 
with  the  head  in  this  position.  The  left  ear  is  then  douched  and 
the  same  procedure  carried  out.  If  the  caloric  test  applied  to  one  of 
these  "border-line"  cases  shows  only  a  slight  impairment  of  the 
responses  from  each  ear,  the  candidate  is  qualified.  If  instead  of 
40  seconds  of  douching,  there  was  required  not  more  than  90  seconds 
of  douching  to  elicit  normal  responses,  the  applicant  is  not  rejected. 
Care  should  be  taken  to  be  certain  that  the  cold  water  is  reaching 
the  drumhead  during  this  caloric  test,  as  wax  or  other  obstruction 
in  the  external  canal  would  interfere  with  the  responses  in  a  per- 
fectly normal  individual. 

After  carefully  considering  the  foregoing  the  neurologist  and  the 
general  diagnostician  can  not  fail  to  be  struck  with  the  compre- 
hensive character  of  these  vestibular  tests,  for  frequently  they  are 
looked  upon  as  ear  tests  only.  Six  months  ago  one  of  the  greatest 
otologists  of  Europe  in  discussing  these  tests  raised  the  question  as 
to  the  necessity  or  advisability  of  including  in  aviation  examinations 
the  past-pointing  and  falling  tests,  his  contention  being  that  in  test- 
ing nystagmus  onl3%  one  secures  definite  evidence  of  the  functional 
state  of  the  semicircular  canal  end-organs  of  the  internal  ear.  When 
his  attention  was  drawn  to  the  fact  that  in  testing  the  past-pointing 
and  falling  in  addition  to  the  nystagmus  one  establishes  definitely 
the  functional  intactness,  (1)  of  the  various  afferent  paths  and 
the  intracranial  structures  through  which  they  pass,  (2)  of  the 
cerebral  cortical  centers  and  their  transcortical  association  tracts, 
(3)  the  efferent  cerebral  paths  and  the  nuclei  through  which  they 
pass,  (4)  the  cerebellar  nuclei  and  correlation  paths  to  and  from 
cerebellar  cortical  centers,  (5)  various  portions  of  Pons  and  Medulla 
Oblongata,  his  attitude  was  completely  changed  and  he  became  a 
firm  advocate  of  the  complete  testing  of  nystagmus,  past-pointing 
and  falling  as  a  routine  procedure. 

It  can  not  be  emphasized  too  strongly  that  the  vestibular  tests 
are  not  only  ear  tests ;  in  addition  they  actually  test  very  extensively 
a  large  portion  of  the  central  nervous  system. 

Certain  infectious  diseases  are  known  to  manifest  a  predilection  to 
attack  the  vestibular  apparatus.  Acute  toxic  end-organ  disease  and 
neuritis  of  the  VIII  nerve  are  well  recognized  complications  of 
mumps,  typhoid,  and  some  of  the  commoner  epidemic  infections; 
syphilis  is  particularh'-  prone  to  attack  the  VIII  nerve.     Permanent 


240  AIB  SERVICE  MEDICAL. 

impairment  of  function  of  the  vestibular  apparatus  in  varying 
degrees  ensues  upon  any  such  attack.  It  therefore  becomes  neces- 
sary to  reexamine  fliers  at  regular  intervals  in  order  to  make  cer- 
tain that  no  functional  deterioration  of  the  vestibular  apparatus 
has  taken  place.  Regular  examinations  should  be  made  at  intervals 
of  about  eight  weeks.  Special  examination  should  be  made  at  once 
of  any  flier  who  manifests  unusual  failure  to  negotiate  air  maneuvers 
with  ordinary  skill. 

3.  Otologic  Problems  Under  Consideration  at  the  Medical 

Research  Laboratory. 

The  first  otologic  problem  attacked  in  the  Medical  Research  Labor- 
atory was  the  effect  of  low  oxygen  on  the  phenomena  of  nystagmus 
and  past-pointing.  It  has  been  demonstrated  by  the  cardiovascular 
and  physiological  departments  that  deleterious  effects  of  low  oxygen 
are  noted  in  connection  with  the  cardiovascular  and  respiratory 
systems.  As  was  to  be  expected,  before  low-oxygen  effects  on  the 
internal  ear  motion-sensing  apparatus  could  be  demonstrated,  cardio- 
vascular and  respiratory  effects  became  manifest.  Therefore,  it  has 
thus  far  been  difficult  to  carry  these  ear  tests  to  a  satisfactory  con- 
clusion. In  these  examinations  the  rotating  chair  was  placed  in  the 
low-presure  tank  with  the  subject  and  observers.  After  having  at- 
tained a  height  of  5,000  feet,  the  candidate  was  exposed  to  the 
effects  of  this  altitude  for  5  minutes,  when  the  routine  nystagmus  and 
past-pointing  experiments  were  carried  out.  The  same  procedure 
was  repeated  at  varying  altitudes  up  to  18,000  feet.  These  findings, 
reported  in  detail  in  another  article,  showed  no  consistent  variations 
from  the  responses  obtained  at  sea  level.  We  may,  therefore,  with  a 
fair  degree  of  safety  assume  that  at  altitudes  up  to  18,000  feet  no 
marked  changes  in  this  function  of  the  internal  ear  occur  as  the 
result  of  low  oxygen.  The  cochlear  portion  was  similarly  unaffected 
at  these  altitudes. 

During  these  experiments  abundant  opportunity  was  afforded  to 
examine  a  large  number  of  drumheads — both  of  the  candidates  and  of 
the  observers.  Experimental  work  in  the  laboratory  has  confirmed 
the  practical  observations  of  fliers — that  middle-ear  difficulties  oc- 
cur during  descent  rather  than  ascent.  One  point  has  been  estab- 
lished without  question,  that  the  amount  of  injection  of  the  drum- 
head is  directly  proportionate  to  the  degree  of  patulence  of  the 
Eustachian  tube.  Intense  pain  in  the  middle  ear  and  down  the  neck 
was  experienced  by  many  subjects,  who  showed  on  examination,  to 
have  moderate  or  severe  congestion  of  the  naso-pharynx.  One  case 
was  extremely  illuminating  and  shows  that  we  must  not  conclude 
that  because  atrophic  rhinitis  is  present,  the  tubes  must  necessarily 
be  patulous.    One  of  the  examining  medical  officers  had  extremely 


AIE   SERVICE   MEDICAL.  241 

atrophic  and  badly  retracted  drumheads  with  scars  from  repeated 
suppurative  attacks.  A  rapid  descent  produced  a  double  bilateral 
perforation,  the  perforations  evidently  occurring  on  the  sites  of 
former  perforations.  A  ^harp  stabbing  pain  was  felt  as  the  observer 
dropped  rapidly  from  14,000  to  1,000  feet,  and  an  examination 
showed  a  bright  red  circle  of  tiny  blood  vessels  surrounding  the  pin- 
point perforations.    The  subsequent  healing  was  uneventful. 

One  of  the  observers,  who  had  a  histbry  of  repeated  attacks  of 
suppurative  otitis  media  in  earl}^  childhood,  developed  a  typical 
acute  purulent  otitis  media  after  several  ascents  in  the  low-pressure 
chamber  on  three  consecutive  days. 

One  of  the  foremost  otologic  problems  constantly  before  the  chief 
cf  the  Air  Medical  Service  has  been  how  much  leeway  can  be  safely 
allowed  in  standard  tests  of  vestibular  functions  and  acuity  of  per- 
ception. As  has  been  mentioned  before,  all  motor  coordinations 
made  by  the  flier  during  flight,  whether  carefully  planned  and  con- 
sciously performed  or  instinctively  and  subconsciously  executed, 
have  only  one  ultimate  expression,  namely,  the  determining  of  his 
relations  with  respect  to  his  environment  and  with  respect  to  the  new 
element  which  is  supporting  his  weight,  the  air.  Either  instinctive 
action  or  carefully  considered  intentional  action  upon  the  part  of 
the  flier  is  determined  entirely  by  information  which  is  coming  into 
liis  possession  concerning  his  relations  with  his  environment.  .  This 
information  can  be  had  by  him  only  through  the  activities  of  his 
special  senses.  But  possession  of  normal  perceptive  end-organs, 
nerve  paths,  and  brain  connections  does  not  constitute  definite  as- 
surance that  the  individual  will  accomplish  satisfactorily  balance 
or  orientation.  Further,  he  may  accomplish  balance  satisfactorily 
and  still  be  completely  disorientated;  or  he  may  be  properly  orien- 
tated and  fail  to  accomplish,  balance  properl3^  The  two  are  inde- 
pendent functions  of  the  mind,  closely  associated,  but  in  no  way 
functionally  interdependent.  On  the  other  hand,  lack  of  normal 
perceptive  apparatus  does  constitute  definite  assurance  that  the  in- 
dividual will  be  physicall}^  less  able  to  accomplish  balance  or  orien- 
tation, or  both,  under  certain  circumstances  under  which  these  would 
be  possible  for  the  man  in  full  possession  of  normal  perceptive  appa- 
ratus. There  are  certain  circumstances  under  which  balancing  can 
be  performed  adequately  even  by  the  man  who  is  possessed  of  less 
than  full  normal  equipment.  There  is  no  doubt  that  man  can  ac- 
complish a  certain  kind  of  flying  blindfolded,  or  without  functionat- 
ing vestibular  apparatus,  or  without  normal  deep  sensibilit3^  Hence 
this  important  air  medical  problem  is  to  study  the  "peak  load" 
requirements,  the  conditions  of  emergency  and  confusion  which  may 
be  encountered  unexpectedly  in  the  air,  and  to  attempt  to  estimate 
carefully  the  minimum  perceptive  equipment  which  would  be  ade- 


242  AIR  SERVICE   MEDICAL. 

quate  under  these  conditions,  to  enable  the  flier  to  negotiate  such 
difficult  and  unusual  phases  of  flying.  There  are  certain  tempera- 
ments, certain  types  of  minds,  certain  intangibly  different  mental 
composites,  "which  determine  the  inability  of  the  individual  to  nego- 
tiate these  critical  points  in  flying,  even  though  he  be  in  full  posses- 
sion of  his  sensory  perceptive  facilities.  "  Self  possession,"  "  cool- 
ness," "  braver}',"  "  sand,"  "  nerve,"  "  presence  of  mind,"  "  judg- 
ment," on  the  other  hand,  added  to  a  perceptive  equipment  of  less 
than  normal  may  determine  the  success  of  an  individual  in  emerging 
safely  from  a  critical  air  situation.  While  this  is  unquestionably 
the  fact,  these  mental  qualities  are  so  intangible,  so  indeterminable, 
and,  above  all,  so  distinctly  not  in  the  category  of  things  physically 
to  be  examined  and  measured  by  the  medical  examiner  that  it  is 
not  deemed  justifiable  for  the  physical  examiner  to  admit  into  the 
Air  Service  or  to  allow  to  remain  in  the  Air  Service  anyone  who  is 
discovered  to  be  lacking  in  acuity  prescribed  for  the  several  special 
senses  known  to  be  prime  requisites  of  the  flier. 

MOTION-SENSING  EXPERIMENTS  IN   LINEAR  UPWARD  AND  DOAVNWARD  DI- 
RECTION.— GROUPS  TESTED. — CONDITION   OF   TESTS^ 

One  of  the  methods  of  approaching  the  problem  of  determining 
what  is  the  relative  value  of  the  various  sensory  contributions  to  the 
individual's  total  knowledge  concerning  motion,  was  a  series  of 
experiments  performed  in  a  bank  of  elevators  capable  of  performing 
vertically  upright  trips  40  stories  in  extent,  a  height  of  over  400  feet, 
at  a  maximum  speed  of  1,000  feet  per  minute.  For  this  purpose  four 
groups  of  individuals  were  selected,  namely,  (1)  normals,  (2)  deaf- 
mutes  totally  lacking  vestibular  perception,  (3)  deaf-mutes  pos- 
sessing vestibular  perceptions  in  various  degrees  below  the  normal, 
and  (4)  tabetics  whose  deep  sensibility  was  impaired  to  various  de- 
grees. These  experiments  were  carried  out  during  a  period  of  six 
weeks,  with  a  view  to  determining  the  average  ability  of  each  group 
to  sense  the  various  vertically  up  and  down  movements  to  which  they 
were  subjected.  The  elevator  shafts  were  entirely  dark,  and  the 
lights  on  the  cars  were  shut  off  during  the  experiments,  so  that  no 
information  reached  the  individual  via  the  visual  tract.  Each  indi- 
vidual of  the  normal  group  was  first  determined  to  be  possessed  of 
normal  vestibular  and  deep  sensibility. 

The  following  is  a  digest  of  the  findings : 

Group  1. 
findings  in  normals. 

ACCELERATION. 

1.  During  acceleration  upward  all  were  able  to  sense  accurately  the 
character  of  the  motion  to  which  they  were  subjected. 


AIR  SERVICE    MEDICAL.  243 

SUSTAINED  SPEED. 

2.  A  slower  sustained  rate  of  speed  immediately  ensuing  upon 
acceleration  upward  was  uniformly  misinterpreted  as  arrest  of  mo- 
tion, or  as  very  slow  motion. 

RETARDATIOX. 

3.  Retardation  to  the  slowest  possible ,  continued  speed  upward, 
ensuing  upon  sustained  speed  upward,  was  universally  sensed  as 
motion  vertically  downward. 

Group  2.  » 

FINDINGS   IN    DEAD   VESTIBULE  DEAF-MUTES. 

4.  The  deaf  mutes  in  Avhom  the  vestibular  function  was  totally 
abrogated  sensed  acceleration  upward  correctly. 

5.  These  individuals  were  uniformly  inconsistent  in  describing 
the  character  of  slow  motion  vertically  upward  at  a  constant  rate  of 
speed,  sometimes  guessing  "  upward  "  and  sometimes  guessing  "  down- 
ward," but  always  acutely  sensitive  to  the  fact  that  they  were  under- 
going motion  of  some  kind. 

6.  Retardation,  ensuing  upon  motion  vertically  upward  at  a  sus- 
tained rate  of  speed,  was  uniformly  correctly  sensed  by  these  indi- 
viduals. 

7.  Arrest  of  motion  ensuing  upon  retardation  or  motion  at  a 
sustained  rate  of  speed  was  uniformly  correctly  sensed  by  these 
individuals. 

8.  In  these  individuals  it  was  impossible  to  produce  the  illusion 
of  reversal  of  motion  by  alteration  in  the  speed  of  the  car.  It  was 
apparent  that  absence  of  hearing  and  vestibular  sense  had  keyed 
up  to  a  high  degree  of  attention  and  sensitiveness  the  deep  sensi- 
bility tract,  though  it  is  not  believed  that  this  observation  justifies 
a  statement  that  the  sensing  of  the  deep  sensibility  impulses  was 
keener  than  that  of  the  normal  individual.  It  seems  certain,  how- 
ever, that  the  attentions  of  these  individuals  to  motion  perceptions 
coming  in  via  the  deep-sensibility  tract  were  more  intense  than  that 
of  the  ordinary  normal  individual. 

Group  3. 

FINDINGS   IN   UVE  VESTIBUM:   DEAF-MUTES. 

9.  Deaf-mutes  in  possession  of  intact  vestibular  apparatus  and 
normal  acuity  of  perception  absolutely  duplicated  the  findings  of 
the  first  group  of  full  normal  individuals  tested,  as  shown  in  items 
1,  2,  and  3  of  this  digest  of  results. 

8911&— 19 17 


244  AIR  SERVICE   MEDICAL. 

10.  Deaf-mutes  in  whom  acuitj'  of  vestibular  perception  was  re- 
duced to  an  index  represented  bj^  two  or  three  seconds  duration  of 
nystagmus  and  no  past-pointing  and  almost  absent  falling  were 
able  to  sense  acceleration  vertically  upward  correctly  and  failed  to 
identify  slower  motion  at  a  sustained  rate  of  speed  upward,  but 
sensed  the  motion  very  positively,  though  labeling  it  at  times  "  mo- 
1  ion  downward  "  and  at  other  times  "  motion  upward  "  ;  they  were 
able  to  detect  retardation  and  arrest  keenly,  but  did  not  experience 
the  illusion  of  reversal  of  motion  either  following  acceleration,  re- 
tardation, or  arrest  of  motion. 

Group  4. 
findings  in  tabetics.  - 

11.  Tabetics  in  whom  vestibular  tests  had  demonstrated  the  pres- 
ence of  normal  vestibular  functions  were  roughly  of  two  classes — 
die  lower  or  dorso-lumbo-sacral  type  and  the  higher  or  the  cervico- 
dorsal  type.  Both  types  evidenced  a  satisfactory  ability  to  sense 
acceleration  of  motion  vertically  upward;  slower  motion  at  a  sus- 
tained rate  of  speed  ensuing  upon  this  acceleration  upward  was  not 
sensed  at  all  by  either  type :  retardation  following  motion  vertically 
upward  at  a  sustained  rate  of  speed  was  sensed  as  motion  downward 
by  both  types.  Particularly  striking  was  the  continuation  over  long 
periods  of  time  of  the  sensing  of  motion  downward  by  the  first  type 
of  tabetics  when  arrest  of  motion  ensued  upon  retardation  vertically 
upward.  Several  of  these  cases  continued  to  indicate  motion  down- 
ward for  from  30  to  60  seconds  following  total  arrest  of  motion. 
This  was  not  the  case  with  the  second  type  of  tabetics,  several  of 
whom,  however,  did  indicate  sensation  of  motion  downward  for  a 
few  seconds  following  total  arrest  of  motion. 

DOWNWARD  MOTIONS. 

12.  Acceleration  of  motion  downward  from  the  fortieth  floor  was 
correctly  sensed  by  normals,  both  types  of  deaf-mutes,  and  both  types 
of  tabetics. 

13.  Slower  motion  downward  at  a  sustained  rate  of  speed  ensuing 
upon  rapid  acceleration  downward  was  sensed  by  the  normals  uni- 
versally, as  either  complete  cessation  of  motion  or  extremely  slow- 
motion  in  a  downward  direction;  this  was  also  the  case  with  the 
second  group  of  deaf-mutes,  those  in  possession  of  vestibular  func- 
tions; the  first  groups  of  deaf-mutes  were  unable  to  sense  the  chai- 
acter  of  sustained  motion  downward  accurately,  but  more  frequently 
guessed  "downwards"  than  "upwards":  the  tabetic  of  either  type 
indicated  almost  invariablv  arrest  of  motion. 


AIE  SERVICE    MEDICAL.  245 

14.  Ketardation  downward  ensuing  upon  motion  at  sustained  rate 
of  speed  downward  was  sensed  as  arrest  of  motion  or  as  slow  motion 
upward  by  the  normal  group  and  by  the  deaf-mutes  in  possession  of 
vestibular  function  and  by  both  types  of  tabetics.  This  confusion  of 
sensing  between  arrest  or  slow  motion  upward  was  consistent  with  all 
members  of  these  groups,  but  individuals  in  each  group  varied  in 
their  answers,  one  individual  sometimes  indicating  arrest  and  at  other 
times  indicating  slow  motion  upward.       * 

15.  ^^jrest  of  motion  ensuing  upon  retardation  downward  was  uni- 
formly indicated  as  slow  motion  upward  by  the  group  of  normals; 
the  group  of  deaf-mutes  in  posse^ision  of  vestibular  function  sensed 
this  as  slow  motion  upw^ard  only  for  a  second  or  two  and  then  indi- 
cated properly  total  arrest  of  motion ;  the  group  of  deaf-mutes  totally 
lacking  vestibular  perception  uniformly  indicated  correct  perception 
of  arrest  of  motion  on  the  instant;  both  types  of  tabetics  indicated 
sensation  of  motion  vertically  upward,  and  this  sensation  continued 
for  a  much  longer  period  of  time  than  in  the  normal  group. 

The  conclusions  from  the  above-outlined  experiments  are  that 
(A)  the  normal  individual,  the  deaf-mute  whose  vestibular  function 
is  unimpaired,  and  the  tabetics  whose  vestibular  functions  are  unim- 
paired seem  to  be  almost  equally  sensitive  to  acceleration  either  up- 
Avard  or  dowmw^ard:  (B)  during  slower  motion  at  a  sustained  rate  of 
speed  upw^ard  or  downward  the  deaf-mute  whose  vestibular  function 
has  been  totally'  abrogated  is  totally  unable  to  sense  accurately  the 
character  of  the  motion  to  which  he  is  subjected,  but  he  is  keenly 
sensible  of  being  subjected  to  some  kind  of  motion;  whether  this  is 
vertically  upward  or  vertically  downward  seems  to  be  pure  guess- 
work. The  other  individuals  tested  all  evidenced  sensory  illusion 
and  always  in  the  shape  of  a  relative  reversal  varying  in  degree  be- 
tween a  sense  of  partial  or  complete  arrest  of  motion  and  inception  of 
motion  in  the  opposite  direction.  This  latter  was  more  marked  in 
the  tabetic.  This  would  seem  to  indicate  that  in  general  the  quantita- 
tive perception  of  motion  at  a  sustained  rate  of  speed  lies  more  par- 
ticularly within  the  province  of  the  deep  sensibilities;  the  qualitative 
perceptioji — that  is.  determination  of  the  exact  direction  of  the 
motion — lies  within  the  province  of  the  vestibular  component  in  the 
total  composite  of  motion-perceiving.  (C)  Susceptibility  to  illusion 
of  a  motion-perceiving  naturally  is  directly  proportionate  to  the  keen- 
ness of  the  ability  to  make  accurate  qualitative  perceptions;  in  other 
words,  the  illusions  of  motion  in  the  absence  of  vision  are  largely,  if 
not  exclusively,  attributable  to  the  vestibular  apparatus. 

It  should  be  added  that  for  the  purpose  of  conducting  these  experi- 
ments especial  control  was  added  to  the  regular  control  of  these  ele- 
vators, and  by  means  of  this  the  accelerations,  retardations,  and  mo 
tions  at  sustained  rates  of  speed  were  accomplished  with  almost  com« 


246  AIS  SEBVIOE  MEDICAL. 

plete  absence  of  jarring  or  friction.  The  use  of  magnetic  brake 
control  adjusted  to  extreme  nicety  and  the  elunination  of  all  loose 
connections  and  joints  eliminated  sound  almost  completely;  the  visual 
element  of  motion-sensing  was  absolutely  eliminated  by  the  conduct- 
ing of  the  tests  in  perfect  darkness;  tactile  impulses  were  almost  com- 
pletely eliminated  by  lining  the  entire  car  with  thick  blankets,  pro- 
tecting the  subjects  from  access  of  air  currents  to  the  skin  throughout 
the  experiments. 

EXPERIMENTAL  STUDIES  ON  "  THE  FEEL  OF  THE  AIRSHIP." 
DEAF-MUTES   AND  NOKMALS. 

A  physiologic  function  which  is  peculiarly  important  in  aviation 
as  contrasted  with  all  other  branches  of  the  service  is  that  of  equili- 
bration. Nothing  could  bett-er  illustrate  this  peculiar  importance  of 
the  inner  ear  than  a  comparative  study  of  those  with  normal  inner 
ears  as  contrasted  with  those  of  destroj'ed  inner  ears — deaf-mutes. 
A  series  of  experiments  was  conducted  in  actual  flights.  Those  with 
normal  inner  ears,  when  blindfolded,  were  able  to  detect  motion 
changes  accurately  during  the  flight,  whereas  blindfolded  deaf-mutes 
Avith  destroyed  labyrinths  were  not. 

In  order  to  appreciate  the  part  that  the  ear  mechanism  plays  in 
aviation,  all  that  any  physician  need  do  is  to  take  a  flight  in  an 
aeroplane.  As  you  guide  an  aeroplane  in  a  straight  flight,  your 
incessant  effort  is  to  correct  minute  deviations  from  the  level  posi- 
tion ;  the  countless  and  continuous  changes  of  movement  in  all  direc- 
tions are  counteracted  b.y  tiny  movements  of  the  joy  stick.  In  your 
first  flights,  when  instructor  is  guiding  the  plane,  you  watch  the  jo}^ 
stick  in  front  of  you  and  you  notice  that  it  is  moving,  ever  so  little, 
this  way  and  that,  in  response  to  stimuli  in  the  detection  of  changes 
of  position.  This  sense  of  the  "  detection  of  movement "  is  what  the 
experienced  aviator  calls  "the  feel  of  the  airship*";  it  is  that  sense 
which  distinguishes  the  born  flier  from  the  mechanical  flier,  who  is 
forced  to  rely  upon  his  sight  in  the  guiding  of  the  plane.  The 
Almighty  gave  certain  sense  organs  to  man;  if  there  is  any  indi- 
vidual who  preeminently  needs  a  normal  sensing  of  movement,  it  is 
obviously  the  aviator.  The  turning-chair  and  douching  tests  enable 
us  to  determine  whether  the  internal  ears  and  all  the  intracranial 
pathways  from  the  internal  ears  are  functioning  normally. 

WHAT  IS   "  FEEI-  OF  THE  AIKSHIP  "  7 

One  of  the  terms  most  commonly  used  in  aviation  is  "  the  feel  of 
the  airship."  It  had  its  origin  at  the  beginning  of  aviation  and  seems 
to  be  a  phrase  which  in  the  mind  of  the  practical  flier  covers  every- 
thing which  goes  to  express  a  trained  aviator's  skill  in  the  proper 


AIR  SEEVICE   MEDICAL.  247 

and  semiautoniatic  control  and  balance  of  an  airship.  Some  men 
give  evidence  of  possessing  this  sense-complex  during  the  first  one 
or  two  hours  of  instructions ;  others  never  acquire  it,  and  still  others 
show  it  in  such  a  moderate  degree  that  they  are  always  looked  upon 
with  apprehension  by  instructors,  who  feel  that  such  men  are  not  to 
be  depended  upon  in  an  emergenc}'. 

Very  few  trained  pilots  can  give  any  c^ear  explanation  of  what  is 
meant  by  the  term,  except  to  say  that  if  the  beginner  does  not  possess 
it  he  will  never  be  able  to  make  a  first-class  pilot.  Some  explain  it 
by  a  keen  sense  of  motion,  some  by  general  physical  dexterity,  some 
by  a  keen  sense  of  vision,  and  some  would  seem  to  credit  it  to  an 
inborn  special  sense  of  some  kind.  That  some  such  sense  or  com- 
bination of  senses  exists,  there  can  be  no  question.  This  general  fact 
has  been  appreciated  by  scientific  men  from  the  start,  and  much  of 
the  work  of  the  Medical  Research  Laboratory  has  been  directed, 
consciously  or  unconsciously,  toward  scientific  explanation  of  this 
sense-complex. 

Evidentlv  motion-sensina:  must  be  intimatelv  related  with  this 
proper  "  feel  of  the  airship."  As  pre^  iously  stated,  motion-sense  is 
dependent  upon  information  derived  from  (1)  muscle  sense,  (2) 
sight,  (3)  vestibular  sense,  and  (4)  tactile  sense. 

OBSERVATIONS    UPON    MOTION-SENSING    DURING    AIRPLANE    FLIGHTS, 
DEEP   MtISCUI.AK   SENSIBILITY  STUDIED   BY  ELIMINATION. 

The  purpose  of  this  study  was  to  tr}'',  by  elimination  of  any  two 
of  the  first  three  factors,  to  estimate  the  value  of  the  third.  The 
fourth,  tactile,  may  be  ignored,  being  constant  in  all  cases.  This  can 
be  done  as  follows :  Blindfolding  eliminates  sight :  the  use  of  deaf- 
mutes  with  destroyed  vestibular  apparatus  eliminates  the  vestibular 
sense;  blindfolding  these  deaf-mutes  eliminates  sight  and  vestibular 
sense,  leaving  the  deep  sensibilitj'-  as  the  remaining  factor.  Experi- 
mental study  with  cases  of  tabes  and  other  similar  cases,  where  the 
deep  sensibility  is  invohed,  are  now  being  carried  on  and  will  give 
ns  further  data  on  deep  sensibility. 

TILTING   PEBCEPTION. 

It  has  been  shown  by  various  observers,  experimenting  upon  thou- 
sands of  aviation  applicants,  that  there  exists  a  very  clear  appre- 
ciation of  tilting.  If  a  chair,  balanced  on  one  point,  is  so  slowly 
tilted  that  a  man  seated  in  it  can  not  sense  the  motion,  there  comes 
a  time  when  he  appreciates  that  he  is  tilted.  Laboratory  experiments 
of  this  sort  have  been  repeated  in  the  air  under  practical  flying 
conditions.  At  first  glance  it  would  seem  that  the  experimental 
errors  in  such  a  study  would  be  overwhelming,  but  a  more  extended 


248  AIR  SERVICE   MEDICAL. 

investigation  in  the  plane,  at  various  altitudes  and  under  various 
weather  conditions,  corrects  this  impression  to  the  extent  that  for 
;i  practical  study  of  the  "  feel  of  the  airship,"  theoretical  experimental 
errors  can  be  disregarded. 

POINTS   IN   EXPERIMENTS   TO   BE   NOTED. 

In  order  to  get  at  normal  responses  under  actual  air  conditions, 
five  points  must  be  observed:  (1)  Subjects  with  previous  flying  ex- 
perience must  be  eliminated ;  (2)  normal  individuals  must  be  selected, 
Avho  are  not  alarmed  by  the  thought  of  a  first  flight,  and  who  have 
trained  powers  of  observation;  (3)  a  professional  pilot  of  years  of 
flying  practice  must  be  used  whose  experience  would  enable  him  to 
appreciate  the  problems  and  hold  the  ship  at  the  given  angles  with 
the  greatest  degree  of  accuracy  in  spite  of  unfavorable  atmospheric 
conditions,  and  a  clinometer  used  by  him  to  measure  angles  of  tilt ; 

(4)  the  same  plane  must  be  used  throughout  the  experiments;  and 

(5)  the  intercommunicating  phone  system  must  be  used  betw^een 
pilot  and  subject. 

KIND  OV  SUBJECTS   SELECTED. 

For  purposes  of  study,  15  candidates  were  selected  from  the  Sur- 
geons in  the  Medical  Research  Laboratory.  Chart  I  is  a  gi-aphic 
diagram  of  the  results  of  the  experiments  on  normal  individuals 
who  have  never  had  any  previous  experience  in  the  air.  The  sub- 
jects were  blindfolded,  were  then  taken  up  in  the  plane,  and  the 
'naneuvers  indicated  were  carried  out.  The  lower  blue  line  shows 
/ne  movements  actually  executed  by  the  plane.  The  upper  red 
broken  line  shows  the  movements  the  subject  felt  were  being  executed. 

EXPLANATION  OF  CHABTS  I  AND  CHARTS  II  AND  III. 

There  is  a  very  important  difference  in  the  nature  of  carrying 
out  the  maneuvers  in  Chart  I  and  Charts  II  and  III.  In  the  first 
type  of  experiments,  conducted  in  Chart  I,  the  positions  were 
changed  by  markedly  quick  movements  of  the  plane,  i,  e.,  the  up^ 
ward  motion  was  the  sudden  zoom  upward,  the  downward  motion 
was  a  quick  almost  vertical  dive  downward,  the  banks  to  the  riglu 
and  left  were  done  quickly,  and  the  turns  on  the  horizontal  plane 
were  made  as  sharp  as  possible. 

If  a  quick  zoom  is  made,  the  feeling  is  that  you  are  being  thrown 
against  the  seat  by  centrifugal  force  and  in  a  quick  steep  bank  a 
similar  sensation  is  noticed.  In  the  start  of  the  nose  dive  one  is 
throM n  against  the  belt  by  the  action  of  the  centrifugal  force,  and 
it  is  not  a  matter  of  wonder  when  the  candidate  interchanges  in  his 
mind  movements  in  which  the  most  prominent  element  is  the  cen- 
trifugal action  forcing  his  body  against  seat  or  belt.    We  also  i'ound 


Chart  1  represents  the  curves  of  normal  in- 
dividuals during  their  first  flights.  The 
blue  line  represents  evolutions  actually 
performed  by  the  machine,  the  red  line 
the  evolutions  the  subject  thought  were 
being  carried  out.  Where  the  line  is 
broken,  the  subject  had  no  idea  of  what 
was  going  on. 


Note. — Upper  line  on   the  original   chart  is   red, 
lower    line    is    blue. 


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(Miart  2A  represents  tlie  subjects'  appreciation 
of  tlie  smallest  angle  in  a  downward  or  up- 
ward   direction. 

Chart  2B  represents  the  subjects'  appreciation 
of   the   smallest   angle   in   a   bank. 

The  stalling  angle  of  the  machine,  past  which 
it  is  unable  to  execute  these  evolutions  is 
70  degrees  up.  40  degrees  down.  8.5  degrees 
on  the  banks. 


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AIR  SERVICE   MEDICAL.  249 

that  if  the  right  and  left  turns  were  kept  in  a  true  horizontal  plane 
without  banking,  that  it  is  very  difficult  to  differentiate  between  the 
two  on  account  of  the  large  size  of  the  circle  it  was  necessarv  to 
describe  in  making  these  turns  without  side-slip.  A  short  analysis 
of  the  different  observation  flights  seem  to  show  that  the  general 
powers  of  observation  are  not  improved  during  an  individual's  first 
flights.  In  fact,  they  are  frequently  impaired  on  account  of  excite- 
ment and  apprehension,  and  a  short  analysis  of  the  personalities  of 
these  subjects  tends  to  explain  many  of  the  errors. 

CASK  HISTORIES. 

Case  I.  experiments  1  <ind  2,  Chart  I. — Young  man.  not  acute  ob- 
server, though  not  particularly  nervous.  Made  one  fundamental 
error  on  first  flight  and  failed  to  sense  banks  or  slow  horizontal  turns. 
On  second  flight  he  made  no  fundamental  errors,  simply  mistaking 
right  and  left  horizontal  slow  turns. 

Case  II,  experiments  3  and  Jf,  Chart  I. — A  middle-aged  man,  badly 
scared  on  first  flight  and  was  all  at  sea.  On  second  flight  was  calmer 
and  made  no  fundamental  errors,  confusing  right  and  left  slow  hori- 
zontal turns  only. 

CojSe  III,  experiments  5  and  6,  Chart  I. — A  cool  phlegmatic  indi- 
vidual. He  mistook  turns  for  banks  during  the  first  flight,  but  made 
no  errors  on  his  second  flight. 

Case  /F,  experiments  7  and  8,  Chart  I. — A  nervous  individual.  Did 
fairly  well  on  his  first  flight  and  improved  markedly  on  his  second, 
making  no  errors. 

Case  V,  experiments  9  and  10  and  11,  Chart  I. — A  young  man,  not 
particular!}^  a  good  observer  and  very  nervous  over  his  flight.  He 
got  very  little  correct  in  his  first  experiment  (9),  appreciating  cor- 
rectly only  horizontal  flight,  marked  upward  and  downward  move- 
ments, and  entirely  missed  right  and  left  horizontal  turns  and  right 
and  left  acute  banks.  His  second  flight  showed  considerable  improve- 
ment, appreciating  correctly  four  out  of  seven  maneuvers,  as  against 
three  in  the  first  flight,  but  far  less  than  the  others.  In  his  third  ex- 
l)t'riment  (experiment  13)  he  made  only  one  bad  mistake  in  iipi)re- 
(iating  seven  maneuvers. 

Case  VI,  experiments  12  and  13,  Chart  I. — This  man  has  an  un- 
usual mentality;  he  is  noted  for  his  muscular  dexterity,  is  an  amateur 
sleight-of-hand  performer  and  a  close  observer  under  all  conditions. 
He  made  no  mistakes  in  either  flight. 

Case  VII,  experiment  IJi.,  Chart  I. — A  highly  trained  clinical  ob- 
server, has  an  extremely  keen  mind,  adventurous  in  spirit,  and  has 
large  experience  in  mountain  climbing  and  in  laboratory  work  at 
high  altitudes.    He  made  no  mistakes. 


250  AIR  SERVICE   MEDICAL. 

Case  VI 11,  experiments  15  and  16,  Chart  I. — A  fair  observer  only. 
In  his  first  flight  he  did  not  try  to  guess  as  many  of  the  more  nervous 
ones  did,  therefore  the  dotted  line.  The  second  flight  showed  im- 
provement, making  only  one  fundamental  error. 

Case  IX,  experiments  17  and  18. — A  man  over  50  years  of  age,  was 
very  nervous  about  his  first  flight,  but  improved  somewhat  during  the 
second,  still  making  several  fundamental  errors. 

Case  X,  experiments  19  and  20,  Chart  I. — A  trained  physiologic 
observer,  cool  and  calm,  and  made  no  mistakes  of  any  kind. 

Case  XI,  experiment  21,  Chart  I. — Highly  strung  j^oung  man,  very 
tense ;  made  only  one  error  on  his  only  flight. 

EXPLANATIONS  OF  CHART  II,  III,   AND  IV. 

Charts  II,  III,  and  IV  represent  a  study  of  the  ability  to  detect 
gradual  departures  from  the  horizontal  flying  line.  In  contradis- 
tinction to  the  first  series  of  observations  the  endeavor  here  was  to 
make  the  change  in  the  angles  so  gradual  that  the  .candidate  would 
appreciate  his  change  from  the  horizontal  in  addition  to  sensing  the 
forward  movement  of  the  plane.  The  endeavor  was  to  eliminate 
suddenness  in  change  of  direction  as  much  as  possible.  They  were 
conducted  with  the  greatest  care  and  only  during  ideal  weather. 
The  angles  were  checked  by  using  a  clinometer  and  every  effort 
possible  was  made  to  eliminate  experimental  error.  The  intercom- 
municating phone  system  was  used.  As  soon  as  a  proper  altitude 
was  reached,  where  the  air  was  smooth,  the  subject  blindfolded  him- 
self and  as  soon  as  he  was  able  to  appreciate  whether  he  was  going 
up  or  down,  or  banking  to  the  left  or  to  the  right,  he  would  so  report 
to  the  pilot.  The  pilot  would  then  maneuver  the  plane  to  repeat  this 
angle  from  6  to  10  times  or  until  he  was  positive  of  the  smallest, 
angle  that  the  subject  was  capable  of  appreciating,  when  he  would 
write  down  his  result.  The  remarkable  similarity  of  the  results  is 
in  itself  proof  that  the  experimental  errors  were  slight,  or  at  least 
were  about  equal  in  all  cases  and,  therefore,  to  be  neglected. 

CHART    2-A. OBSERVATIONS    UPON    MOTION-SENSING    DURING    AIRPLANE    FLIGHTS. 

In  this  series  of  experiments  some  of  the  subjects  had  never  flown, 
while  others  had  had  a  few  flights  previously  in  the  other  series  of 
experiments.  It  is  to  be  noted  that  in  this  series  the  downward  angle 
was  detected  in  every  case  more  accurately  than  the  upward  angle; 
the  upward  angle  was  less  accurately  detected  by  men  making  their 
first  flight.  One  of  these  beginners  was  unable  to  detect  the  upward 
angle  even  to  70  degrees,  the  stalling  angle  of  the  machine.  Subse- 
quent examination  showed  that  this  man's  vestibular  reactions  were 
very  much  subnormal,  as  evidenced  by  10  seconds'  duration  of  nystag- 


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ATE  SERVICE   MEDICAL.  251 

miis,  no  past-pointing,  and  only  very  slight  tendency  to  fall.  The 
general  average  of  these  upward  and  downward  experiments  show 
upward  angle,  17  degrees ;  downward  angle,  9  degrees. 

CHART    2-B. 

Chart  2-B  represents  a  series  of  experiments  similar  to  those  just 
described,  except  that  the  angles  were  bunking  (lateral)  angles 
instead  of  upward  and  downward  (forward)  angles.  This  series  of 
experiments  showed  a  similarity  in  the  ability  to  detect  lateral 
changes  from  the  horizontal.  A  curious  development  was  that  in 
this  series  the  banks  to  the  left  were  more  accurately  detected  by 
the  subjects  than  similar  banks  to  the  right. 

CHAKT   4. 

Chart  4  shows  the  most  interesting  results  of  all.  Seven  deaf- 
mutes  were  the  subjects  of  these  experiments.  Two  showed  normal 
vestibular  function,  four  showed  absolute  lack  of  vestibular  func- 
tion, and  one  showed  a  verv  small  amount  of  vestibular  function 
as  represented  by  three  seconds  of  nystagmus.  The  results  of  these 
experiments  upon  deaf-mutes  are  further  divided  into  three  groups. 
The  findings  of  the  first  groups,  those  with  absolutely  no  vestibu- 
lar function,  showed  total  inability  to  detect  changes  in  the  series 
of  mo^•emeuts  of  the  plane  in  any  of  the  six  flights  per  individual. 
The  results  of  experiments  with  the  second  type  of  deaf-mutes,  in 
which  only  a  vestige  of  vestibular  function  remained,  are  almost 
identical  with  those  of  the  first  group.  The  third  type  of  deaf- 
nnites,  in  full  possession  of  vestibular  function,  showed,  however,  a 
marked  improvement  over  the  others  in  successive  flights,  and  prac- 
tically the  normal  index  as  to  accuracy  of  detection  of  the  move- 
ments of  the  plane  in  the  later  flights. 

CHAST  m. 

Chart  III  consists  of  a  series  of  observations  carried  out  under 
the  same  conditions  upon  three  professional  fliers  and  one  profes- 
sional trick  motor-cyclist.  Their  superiority  in  detecting  angles  is 
at  once  apparent.  Still  more  interesting  is  the  fact  that  the  motor- 
cyclist, who  had  practically  no  flying  experience,  did  not  detect 
angles  as  well  as  the  pilots,  but  still  appreciated  them  better  than 
flid  other  subjects  inexperienced  in  balancing. 

Other  experiments  with  other  normals,  not  noted  on  these  charts, 
convinced  us  that  the  results  so  far  given  represent  very  accu- 
rately the  general  average  in  such  individuals,  and,  therefore,  ex- 
periments of  a  greater  number  were  not  considered  necessary  for 
this  prelimiiiary  study. 


252  AIR  SERVICE   MEDICAL. 


deaf-mutj:  experiments. 


CHART  IV. 

Chart  IV  is.  as  has  been  said,  the  mo^t  interesting  of  all.  Seven 
deaf-mutes  were  selected  whose  labyrinth  findings  are  given  on  the 
edges  of  the  charts.  The  striking  differences  between  these  deaf- 
mutes  and  the  normal  candidates  and  the  still  more  striking  lack 
of  improvement  in  all  their  subsequent  flights  seem  to  be  fairly  con- 
vincing that  for  purposes  of  appreciating  changes  of  position  in 
space  a  properly  functionating  vestibular  apparatus  is  of  great  im- 
portance, and  further,  but  little  can  be  expected  from  deep  sensibil- 
ity when  it  alone  senses  motion.  These  deaf-mutes  were  all  highly 
interested  and  were  keenly  alive  to  the  experiments.  Some  of  them 
were  convinced  that  they  would  prove  able  to  qualify  for  aviation, 
ajid  when  their  charts  were  shown  to  them  their  amazement  was  ex- 
treme. Their  guesses  as  to  the  kind  of  motion  to  which  they  had 
been  subjected  were  of  the  wildest  character.  They  had  nothing 
to  inform  them  except  their  deep  sensibility  and  tactile  sense.  Nose 
dives  and  the  "  zoom  "  or  upward  movements  were  carried  out  at 
such  acute  angles  that  it  was  remarkable  that  they  guessed  as 
inaccurately  as  they  did.  On  close  questioning  many  of  them  ad- 
mitted that  they  were  entirely  "  in  the  dark "  and  felt  as  if  they 
must  tear  the  bandage  from  their  eyes;  in  other  words,  they  were 
completely  lost  in  space,  and  it  is  greatly  to  their  credit  that  they 
were  willing  to  subject  themselves  repeatedly  to  these  more  or  less 
trying  experiences. 

One  of  the  most  important  observations  of  all  is  seen  in  an  ex- 
amination of  Chart  V.  As  a  matter  of  interest,  before  these  subjects 
-were  sent  up,  we  tried  them  walking  a  straight  line  blindfolded, 
which  they  did  in  a  fairly  accurate  manner,  but  when  they  were 
asked  to  maintain  themselves  in  equilibrium  by  standing  on  one  leg 
with  eyes  closed,  they  fell  in  various  directions  and  none  of  them 
were  able  to  stand  at  all  steadily  in  this  position.  After  rapid  rota- 
tion with  the  head  forward  and  eyes  closed,  they  were  quite  as  able 
to  stand  as  they  had  been  before,  showing  no  tendency  toward  the 
normal  falling  response.  They  were  dependent  for  sensory  informa- 
tion in  walking  or  standing  on  one  leg,  etc.,  upon  only  two  sources — 
vision  and  deep  sensibility. 

In  the  angle  experiment,  shown  on  Chart  V.  where  rapid  accelera- 
tion of  motion  was  made,  not  a  single  subject  was  able  to  guess  a 
single  correct  position  in  space.  The  machine  was  brought  up  to  the 
stalling  angle  above,  to  the  extreme  diving  angle  below,  and  to  such 
an  acute  bank  that  the  vertical  control  became  the  rudder,  and  because 
the  change  was  gradually  brought  about,  they  were  still  unable  to 
appreciate  any  deviation    from  the  horizontal.     This  preliminary 


r 

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Chart  5  represents  for  deaf-mutes  what  chart 
2    represents    for    normals. 

Chart    5A    represents    the   snb.lects'    apprecia- 
tion of  the  smallest  angle  in  downward  or 
upwai'd    direction. 

Chart  2B  represents  the  subjects  appreciation 

1 

a 

1 

i 

i 

of  the  smallest  angle  in  bank. 
The  stalling  angle  of  the  machine,  past  which 
it  is  unable  to  execute  these  evolutions  is 

1 ■ 

70  d 
on    1 
It  is  t( 
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122-1 


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122-2 


AlK   SERVICE   MEDICAL.  253 

study  was  made  in  the  hope  that  the  peculiar  impression  which  has 
gone  abroad  and  which  has  done  much  to  block  the  progress  of  the 
selection  of  aviation  candidates — that  the  less  acute  motion-sense  of 
the  inner  ear  was  the  less  dizzy,  and  therefore  the  better  flier  the 
man  would  make,  would  be  corrected. 

The  findings  (covering  seven  days  of  experimental  work,  including 
52  flights)  as  to  the  motion-sensing  of  the»two  deaf-mutes  with  nor- 
mal vestibular  reactions  give  undoubted  evidence  of  gradual  improve- 
ment in  correct  sensing  of  motion;  one  deaf-mute  with  a  vestige  of 
vestibular  function  shows  some  improvement  in  ability  to  sense  mo- 
tion correctly;  four  deaf-mutes  with  no  vestibular  function  show  no 
evidence  of  improvement  in  motion-sensing  ability.  It  must  be  borne 
in  mind  that  such  a  series  of  experiments  should  be  much  greater  and 
should  cover  a  much  longer  period  of  time  if  deductions  of  a  final 
nature  are  to  be  drawn.  The  injection  of  so  many  extraneous  influ- 
ences, such  as  apprehension,  fear,  excitement,  inability  to  focus  at- 
tention, vitiates  to  a  considerable  extent  the  value  of  the  findings  in 
any  individual  flight.  On  the  other  hand,  guesswork  injects  an  ad- 
ditional element  of  unreliability  into  the  findings.  While  analysis 
of  the  charted  records  shows  some  surprising  inconsistencies,  it  is  at 
once  apparent  that  normals  show  no  such  diametrically  opposite 
consecutive  motion-sensing  perceptions  as  the  deaf-mutes.  It  is  dem- 
onstrated by  this  series  of  experiments  that  man's  ability  to  sense 
motion  is  measured  by  his  full  possession  of  visual  acuity,  deep  sensi- 
bility, vestibular  sense  acuity,  and  tactile  sense.  And  particularly, 
that  the  "  feel  of  the  airship  "  which  is  the  sense-complex  that  makes 
for  a  first-class  pilot,  requires  normal  vestibular  motion-sensing. 

4.  Experience  and  Education  in  Motion -Sen sing  and  Fatigue  of 

THE  Vestibular  End-Organs. 

The  possibilities  of  a  person  accustoming  or  educating  himself  by 
constant  rotation  to  estimate  correctly  the  sensations  of  vertigo  or 
disturbed  relations  in  space  have  been  considered,  and  experiments 
Avere  carried  out  with  a  view  to  shedding  light  upon  this  question. 
The  matter  is  one  of  prtictical  importance,  and  upon  it  the  life  of  an 
aviator  may  depend  in  a  critical  moment.  Adjustment  in  seasick- 
ness, in  whirling  dances,  in  acrobatics,  and  in  any  other  line  of  work 
where  rapid  changes  of  spacial  relations  are  necessary  has  long  been 
known.  It  has  been  a  disputed  point  as  to  whether  the  duration  of 
the  nystagmus  in  ^uch  cases  actually  becomes  less  and  less  with 
the  same  stimulus.  By  experiment  it  was  found  that  nystagmus 
occurs  less  in  duration  after  repeated  turnings,  and  the  sensation 
of  vertigo  becomes  less  intense.  The  immediate  shortening  of  dura- 
tion of  nystagmus  and  the  lessening  of  vertigo  in  whirling  dancers 
or  others  ensuing  upon  excessive  stimulation  of  the  vestibular  end- 


254 


AIE   SERVICE   MEDICAL. 


organs  is  a  transitory  fatigue  phenomenon.  The  average  normal, 
whose  nystagmus  time  when  not  fatigued  is  approximately  24  to 
26  seconds,  is  the  man  who  is  physically  most  suitable  for  flying 
training.  Many  experiments  concerning  acute  and  chronic  fatigue 
phenomena  are  now  under  consideration  in  this  laboratory  and  will 
l)c  reported  upon  later.     {See  Editorial  Insert,  p.  S2S.') 

The  whirling  artists,  who  spend  years  in  professional  whirling 
nets,  when  not  fatigued  show  full  normal  responses  to  tests  of  their 
vestibular  apparatus.  Their  art  lies  in  the  education  and  experience 
which  they  have  gained  and  in  the  dexterity  they  have  acquired  in 
the  repeated  performance  of  their  acts.  For  instance,  .a  whirling 
dance  may  be  creditably  performed  by  a  novice,  but  the  professional 
whirling  dancer  will  demonstrate  his  ability  to  stop  dead  still  sud- 
denly without  a  fall,  whereas  the  novice  will  fall,  because  of  the 
vertigo  (or  false  sense  of  motion)  he  experiences  as  a  result  of  his 
whirling.  The  diflFerence  between  the  artist  and  the  novice  lies  in 
the  artist's  ability  to  place  proper  construction  upon  his  false  sense 
of  motion,  experience  and  education  enabling  him  to  estimate  its 
degree  of  falsity  so  correctly  that  he  is  able  to  calculate  his  voluntary 
muscular  control  in  a  manner  that  results  in  his  accomplishing  a 
successful  standing  still.  The  novice,  unpracticed  and  inexperienced 
in  estimating  vertigo,  finds  himself  unable  to  do  so  successfully  and 
falls  to  the  floor. 


TESTS  OF  WHIRLING  ARTISTS,  DANCERS,  AND  EQUILIBRISTS,  FEB.    28,   1918. 


"Zr.  L.,^^  whirling  artist 

Nyat.  R.  26  sec,  L.  24  sec 

JTo  R.  {£• 


P.  P. 


Falls. 


R.  hand  5. 
hand  4. 
I T*-^  T  / 1^'  hand  3. 
^^"^^11.  hands. 
JR.  normal. 
\L.  normal. 


"/.  5.,"  equilibrist 

Nyet.  R.  26  sec,  L.  24  sec. 

fTo  R.  { 

[ToL 

Falls 1^- 

"7.  B.,"  tight  and  slack  wire  artist. 


R.  hand  3. 

L.  hand  1. 

/R.  hand  1. 

•  \L.  hand  3. 


fR.  normal, 
normal. 


Nyst.  R.  28  sec,  L.  33  sec. 

[ToR. 

1toL.{^; 

fR.  normal. 
\L.  normal. 


P.  P. 


Falls. 


/R.  hand  2. 

\L.  hand  2. 

R.  hand  2. 

hand  2. 


"C.  (?.,"  balance  equilibrist. 
Nyst.  R.  25  sec,  L..20  sec. 


P.  P. 
Falls. 


fTo  R.  1^-  ^^°^  ^ 
Ito  L-  {I:  hand  3 


hand  2. 
hand  2. 


■{I 


normal, 
normal. 


Mrs.  "E.  B.,"  whirling  artist. 
Nyst.  R.  34  sec,  L.  35  sec. 


P.P. 
Falls. 


JR.  hand  3. 
■  \L.  hand  3. 
/R.  hand  3. 
'•  \L.  hand  3. 
fR.  normal. 
IL.  normal. 


fToR 
ToL 


"C.  i^.,"  whirling  dancer 
Nyst.  R.  29  sec,  L.  31  sec 

P.  P 


rr.^  Tj  /R.  hand  1. 
^^  ^-  1l.  hand  1. 


Falls. 


fR.  normal. 
\L.  normal. 


AIK   SERVICE   MEDICAL 
"0.,"  whirling  dancer 

Nyet.  R.  27  sec,  L.  28  sec. 
P.  P 


fR.  hand  3. 


Falls. 


F°  ^-  {l."  hand  3. 
"W,.  T    f^-  hand  1. 

1^°^-  \L.  handl. 

JR.  normal. 
■\L.  normal. 


255 


E.  M.,"  head  balancer,  41  years  old,  20 
years'  experience. 


Nyst.  R.  34  sec,  L.  31  sec 
P.  P 


To  R-  {l.  hand  2 


To  L.  I 


R.  hand  3. 
L.  hand  2. 
R.  hand  3. 


Falls. 


[L.  hand  4. 
JR.  normal. 
"\L.  normal. 


"P.  .4.,"  percli  act,  20  years  old,  IS  years     "C.  A.,'^  perch  act,  28  years  old,  IS  years 

experience. 


experience. 

Nyst.  R.  31  sec,  L.  38  sec. 

JTo  R.  { 


P.  P 

Falls 


R.  hand  2, 
L.  hand  1. 


ToL, 


fR.  normal. 
IL.  normal. 


JR.  hand  5. 
\L.  hand  6. 


"  Mrs.  S.,"  whirling  act. 
Nyst.  R.  31  sec,  L.  25  sec. 


P.  P. 

Falls. 


F^  ^-  {l.  hand  3. 


R.  hand  3. 

L.  hand  3. 
iT"^  T    /R-  hand  3. 
^^^  ^-  \L.  hand  3. 
R.  normal, 
normal. 


{? 


ToR 

To  L 

R.  normal. 


^"^  ^-  {l.  hand  3. 


Nyst.  R.  21  sec,  L.  24  sec 
P.  P 

F^"^ {l:  normal 

''Mrs.  S.,"  whirling  act. 
Nyst.  R.  22  sec,  L.  24  sec. 

P.  P 


fR.  hand  1. 

\L.  hand  1. 

R.  hand  2. 


P^alls. 


fm-  T>    /R.  hand  2. 

J ^^^-JL.  hand  2. 
"  It^^  t    JR-  band  1. 

^^°  ^-  \L.  hand  i. 

fR.  normal. 
■\L.  normal. 


CONVERSATION   WITH  "  G  "  AND  "  B,"  PROFESSIONAL  BALLET  DANCERS. 

"Very  little  dizziness  even  when  learning,  but  individual  varia- 
tion; conquest  of  dizziness  depends  upon  acquisition  of  ability  to 
jerk  head  as  dancer  revolves.  Revolving  with  head  not  jerking, 
eyes  open  or  shut,  causes  dizziness.  Refused  to  revolve  jerking  head 
with  eves  shut,  because  it  would  be  sure  to  cause  dizziness  and 
nausea ;  they  were  sure  it  was  much  worse." 

^^  Mrs.  S.,"  aerial  flying  trapeze,'{50  years     "L.  if.,"  head  balancer,  18  years  old,  8  or 
old,  SO  years  in  circus.  9  years  experience. 

Nyst.  R.  17  sec,  L.  18  sec. 
P.  P 


fTo 


K.{: 


R.  hand  3. 
L.  hand  2. 


Falls 


R.  hand  2. 
L.  : 
R.  normal. 


'^^  ^-  {l.  hand  3. 


Nyst.  R.  37  sec,  L.  30  sec 
P.  P 


R.  hand  3. 
L.  hand  2. 
R.  hand  2. 


Falls. 


/I 
\L,  normal. 

Cases  "A"  and  "  B  "  were  tight-rope  walkers. 


|ToR-{L.hand2 

ITo  L-  {I:  hand  4 
JR.  normal, 
1l.  normal. 


Nyst.  R.  26  sec,  L.  26  sec 
P.  P 


To  R.  {J-  ^^^^  3. 
To  L.  {[ 


Falls. 


hand  3. 
R.  hand  3. 
L.  hand  3. 
R.  normal, 
normal. 


'b: 


Nyst.  R.  26  sec,  L.  26  sec. 

fToR. 


P.  P. 


{?: 


hand  3. 
hand  3. 


■{£• 


Im^  J    JR.  hand  3. 
^°  ^-  \L.  hand  3. 


Falls  /^-  normal. 

**^^^ 11.  normal. 


256  AIR  SERVICE   MEDICAL. 

Cases  "  C,"  "  D."  "  E,"  and  "  F  "  were  motordrome  whirling  racers. 
"C,"  26  years  old,  6  years'  experience.       \       "D,"  23  years  old,  5  years'  experience. 

Nyst.  R.  22  sec,  L.  24  sec.  \  Nyst.  R.  26  sec,  L.  26  sec. 

ITn  T?   I^-  liand  3.  |  fm.  t>   JR.  hand  3. 

^°  ^-  \L.  hand  3.  I  p   p  ^°  ^-  \L.  hand  3. 

m„  T    /R.  hand  3.  i  ^- -^ 1^^  t     (R.  hand  3. 
^"^  ^-  \L.  hand  3.  j  l^°  ^-  (l.  hand  H. 

k'oilu                              /^-  normal.                '  „  „  /R.  normal. 

^^"" \L.  normal.  |  ^^^^^ \L.  normal. 

"E,"  26  years  old,  6  years' experience.       I  "  F,"  24  years  old. 

Nyst.  R.  26  sec,  L.  26  sec  j  Nyst.  R.  8  sec,  L.  8  sec. 

fT>/^  T?    /R-  ^and  3.  I  fm„  p    JR.  hand  T. 

p    p  \^°^-  XL.  hand  3.  i  p   p  r "  ^-  IL.  hand  T. 

^-  ^ rp„  T     fR.hand3.  I  ^-  ^ U^  x     fR.handT. 

l^°  ^-  1l.  hand  3.  '  ^^°  ^-  \L.  hand  T. 

T,.-ii„  fR.  normal.  t,^,,  /Falling  absent. 

^^"' \L.  normal.  ^^"^ iFallinl  absent. 

Applicant  "  F  "  was  a  vigorous,  robust  young  man  and  from  all 
appearances  the  most  promising  applicant  of  the  day.  The  caloric 
test  was  given  68°  douche  in  both  right  and  left  ears  with  same  sub- 
normal reaction.  This  man  had  formerlv  ridden  a  motorcvcle  at 
the  rate  of  50  miles  per  hour  on  circular  wall  on  motordrome  and  had 
never  experienced  nausea  or  dizziness.  A  4-j-  Wasserman  and  his- 
tory of  recent  chancre  explained  the  reactions. 

Many  important  practical  applications  may  be  the  outcome  of  these 
experiments.  It  may  ultimately  become  a  routine  method  of  accus- 
toming the  young  pilot  to  the  sensations  of  the  spinning  nose  dive 
and  the  rolling  motion  of  the  airship  by  revolving  exercises.  Most 
important  of  all  may  be  the  possibility  of  teaching  the  prospective 
flier  the  sensations  of  the  loop,  tight  spiral,  and  spinning  nose  dive 
and  how  to  control  himself  during  the  incidental  vertigo  by  daily 
practice  in  some  such  apparatus  as  that  devised  by  Ruggles. 

The  most  common  revolving  motions  of  the  aeroplane  are  the  spiral, 
spinning  nose  dive,  and  the  roll.  In  the  spinning  nose  dive,  or  tight 
spiral,  the  aviator  may  have  his  horizontal  canals  or  his  vertical 
canals  chiefly  afl'ected  according  to  the  position  he  assumes.  Since 
every  individual  is  more  accustomed  to  the  horizontal  canal  stimula- 
tion than  the  vertical  canal  stimulation,  it  is  better  that  he  assume  a 
position  in  which  the  horizontal  canals  are  mainly  stimulated.  In 
spiral  turns,  if  the  aviator  sits  upright,  the  horizontal  canals  are  the 
ones  mainly  stimulated,  and  these  very  slightly,  liecause  of  the  large 
circular  turns.  In  the  spinning  nose  dive  the  ship  noses  vertically 
down,  due  to  the  hea^'y  engine  and  if  the  aviator  remains  in  the  same 
upright  position  as  in  horizontal  flying  he  will  then  concentrate 
stimulation  upon  his  vertical  canals.  But  if  he  bends  forward  as 
the  French  aviators  are  instructed  to  do,  he  will  practicallj^  be  upside 
down  so  that  again  he  will  concentrate  stimulation  upon  the  horizon- 


ATR  SERVICE    MEDICAL.  257 

tal  semicircular  canals.  Physical  directors  have  advised  turning 
movements  as  practice  exercises ;  but  after  all  this  is  only  of  prelimi- 
nary value,  because  experienced  fliers  become  so  accustomed  to  turn- 
ings and  air  antics  that  they,  like  acrobats,  know  where  they  are  at 
all  times  and  are  at  home  in  the  air. 

Space  does  not  permit  in  this  article  to  quote  from  the  histories 
of  aviators  at  the  disposal  of  the  otologic  department  cases  where,  fol- 
lowing impairment  of  the  labyrinth  due  to  mumps  or  syphilis,  a  man's 
flying  ability'  has  been  lost  or  badly  impaired  coincidentally  with 
the  rapid  deterioration  of  his  vestibular  sensory  acuity.  This  is  ad- 
ditional corroborative  evidence  of  the  most  convincing  nature. 

RESUME. 

General  condition  of  aviator's  ears,  nose,  and  throat  must  be  good. 

The  ground  soldier  can  stand  still.  The  aviator  can  not.  Motion 
assumes  great  added  importance  to  the  aviator. 

Motion-sensing,  therefore,  assumes  gi'eat  additional  importance  to 
the  aviator. 

Of  the  senst's  concerned  in  motion-sensing,  the  vestibular  sense  is 
the  only  one  whose  utility  remains  constant;  hence  the  necessity 
of  determining  the  aviator's  possession  of  requisite  vestibular  sense. 

Vestibular  tests  not  onlv  determine  functional  condition  of  this 
portion  of  the  internal  ear  but  give  definite  information  concerning 
the  integrity  of  parts  of  the  medulla  oblongata,  pons,  cerebrum,  and 
particularly  the  cerebellum. 

It  has  been  determined  that  up  to  18,000  feet  there  occurs  no 
marked  functional  change  in  the  vestibular  apparatus. 

Observations  made  in  an  extensive  series  of  blindfold  experiments 
on  normal  persons,  on  persons  with  nonfunctionating  vestibular  appa- 
ratus, on  persons  lacking  hearing  only,  and  on  persons  with  impaired 
deep  sensibilities  indicate  that  perception  of  motion  in  a  linear 
direction — 

(a)  During  acceleration,  is  sensed  most  accurately  by  those  whose 
vestibular  apparatus  is  functionating; 

(b)  At  a  sustained  rate  of  speed  is  sensed  accurately  by  each 
group  except  those  lacking  deep  sensibility ; 

(c)  During  retardation  is  sensed  accurately  by  those  whose  vesti- 
bular apparatus  is  functionating: 

(d)  Arrest  of  motion  ensuing  upon  motion  in  a  linear  direction 
is  most  accurately  detected  by  the  group  lacking  vestibular  function 
but  in  possession  of  unimpaired  deep  sensibilities. 

Experience  in  aeroplane  flights  shows  that  blindfolded  normal 
persons  perceive  motion  changes  accurately;  that  blindfolded  persons 
lacking  normal  ve.stibular  apparatus  do  not. 


258  AIB  SERVICE   MEDICAL. 

Transitory  fatigue  may  be  observed  after  excessive  stimulation  of 
the  vestibular  end-organs. 

Special  ability  to  estimate  correctly  the  degree  of  falsity  of  oft- 
repeated  motion-sensing  illusions  may  be  developed  in  normal  per- 
sons through  experience  and  education.  This  special  ability  enables 
its  possessor  to  maintain  safe  bodily  relation  with  his  ehvironment 
during  the  existence  of  the  motion-sensing  illusions  with  which  he  has 
become  familiar  through  long  experience. 

A  superficial  observation  might  suggest  that  possibly  the  safest 
aviators  would  be  those  lacking  vestibular  function,  such  as  deaf 
mutes,  inasmuch  as  they  are  incapable  of  developing  motion-sensing 
illusions  which,  in  normal  persons,  ensue  upon  spinning  nose  dives  or 
other  whirling  aeroplane  maneuvers.  Possession  of  normal  function- 
ating sensory  end-organs  always  entails  the  possibilities  of  subjec- 
tive sensory  illusions,  but  to  argue  the  advantage  of  lacking  such 
special  sense  end-organs  is  to  reach  the  reductio  ad  absurdum. 

One  who  shows  good  responses  in  the  turning-chair  shows  good 
detection  of  movement  in  the  air;  one  who  shows  poor  responses 
in  the  turning-chair  shows  poor  detection  of  movement  in  the  air. 
There  is  this  direct  relation  between  the  chair  and  the  air  and  the 
air  and  the  chair. 

THE  EAR  IN  STUNT  FLYING. 

Crashes  that  occur  during  "stunt"  flying  are  usually  the  result 
of  something  having  gone  wrong  with  the  pilot.  Hence  it  is  a  perti- 
nent matter  for  medical  investigation.  Just  what  this  something  is, 
is  not  always  clear.  Poor  judgment,  a  sense  of  bravado,  carelessness, 
'•stunting"  at  low  altitudes,  and  sudden  faintness  are  among  the 
reasons  generally  offered  in  explanation  of  these  accidents.  Direct 
testimony  of  the  pilot  is  not  always  available,  since  many  of  the 
crashes  result  fatally.  Neither  are  pilots  who  have  crashed  and 
survived  always  able  to  give  a  clear  and  concise  account  or  analysis 
of  the  causes  of  the  accident. 

Underlying  them  all,  however,  there  runs  a  story  of  momentary 
loss  of  faculties,  resulting  in  a  manipulation  of  controls  without 
deliberate  judgTnent.  Most  accounts  of  crashes  read,  "  The  pilot  went 
into  a  tail  spin  and  failed  to  come  out."  The  story  of  Lieut.  J.  M.  M. 
is  quite  typical  of  those  collected  by  this  department. 

While  flying  he  went  into  a  tail  spin.  This  produced  such  over- 
powering dizziness  that,  not  knowing  what  he  was  doing  or  why,  he 
gi-abbed  the  "  joy  stick  "  and  pushed  it  forcibly  over  and  threw  him- 
seK"  into  another  tail  spin  in  the  opposite  direction.  Before  he  could 
come  out  of  this  he  crashed. 

So  many  of  the  accounts  of  crashes  given  by  pilots  who  did  survive 
emphasize  dizziness  (or  vertigo),  that  the  organ  responsible  for  dizzi- 


VI low  OF  SEMICIRCULAR  CANALS  IN  BASE  OE  SKULL. 


SPINNING  NOSE  DIVE. 


tJHTXTXTTXTri      -VTrkC?!}!     TMl^TT" 


<t*ix'\:tk(^   iVOKI-i  invi: 


AIK  SEKVICE  MEDICAL.  259 

ness  when  an  individual  is  whirled  around,  namely,  the  ear,  was  nec- 
essarily made  the  subject  of  investigation  by  the  Otologic  Depart- 
ment of  the  Medical  Research  Laboratory  at  Mineola,  N.  Y.  Experi- 
ments which  involved  the  whirling  of  individuals  point  conclusively 
to  the  fact  that  Stunt  Flying  is  essentially  an  Ear  Problem. 

By  visualizing  the  position  of  the  pilot  as  he  is  whirled  in  the 
various  stunt  evolutions,  it  was  found  that  by  reproducing  a  similar 
whirling  in  the  apparatus  it  was  possible  to'simulate  all  the  subjective 
effects  of  stimt  flying. 

Lieut.  J.  F,  D.  (150  hours  in  the  air)  was  placed  in  a  certain 
position  and  whirled.  He  volunteered  the  information  that  his 
sensations  were  identical  with  those  experienced  when  coming  out 
of  a  spinning  nose  dive.  When  placed  in  the  apparatus  in  a  certain 
different  position  and  whirled,  he  stated  that  his  sensations  were  those 
experienced  when  coming  out  of  a  tight  spiral.  Lieut.  W.  E.  R.,  an 
experienced  pilot,  when  placed  in  the  same  position  as  Lieut.  D.'s 
first  position  made  the  statement  that  his  sensations  were  identical 
with  those  of  his  predecessor,  saying,  "That  is  exactly  like  coming 
out  of  a  spinning  nose  dive."  When  placed  in  another  position  and 
whirled  he  said,  "  Now  I  feel  like  coming  out  of  a  loop."  These  facts 
were  confirmed  by  similar  experiments  on  other  aviators. 

Since  being  whirled  in  an  aeroplane  produces  effects  identical 
with  those  resulting  from  being  whirled  in  a  laboratory  device, 
such  as  the  turning-chair,  or  other  forms  of  apparatus,  designed 
for  that  purpose,  we  are  furnished  with  an  accurate  and  convenient 
means  of  studying  the  various  vertigo  effects  of  ear  stimulation 
produced  by  evolutions  in  the  air,  and  deductions  derived  from  this 
experimental  stimulation  are  true  and  applicable  to  stunt  flying. 
The  facts  gleaned  were  so  exactly  in  accordance  with  our  knowledge 
of  the  ear  as  a  '"  motion-sensing  apparatus "  that  they  were  simply 
corroborations  of  certain  well-known  otologic  principles. 

Now,  what  are  these  established  facts  or  principles? 

1.  In  each  ear  we  have  three  semicircular  tubes  or  canals,  contain- 
ing fluid,  so  placed  that  they  are  at  right  angles  with  each  other. 
Because  of  this  arrangement,  no  change  of  position  of  the  indi- 
vidual is  possible  without  producing  some  movement  of  fluid  in  one 
or  more  of  the  canals.  Movement  of  the  fluid  in  these  canals  sends 
messages  to  the  brain  which  are  there  interpreted  as  body  movement. 
Hence,  the  ears  constitute  the  motion-sensing  organs  of  the  body. 

2.  When  an  individual  is  whirled,  be  it  in  the  laboratory  or  in  an 
aeroplane,  there  is  produced  a  circulation  of  this  fluid  in  certain 
definite  canals  and  planes.  Now,  if  the  turning  be  suddenly  altered 
or  stopped  or  if  the  aeroplane  comes  out  of  rotating  maneuver,  the 
fluid  in  the  canals  continues  to  move  in  its  former  plane  by  sheer 

89U8— 19 18 


260  AIR  SERVIOE   MEDICAL. 

force  of  its  momentum.  This  circulation  of  the  fluid  (by  momentum) 
is  interpreted  by  the  brain  as  body  movement,  but  not  being  in  ac- 
cordance with  fact,  the  body  having  ceased  to  revolve,  constitutes 
vertigo  or  dizziness,  and  is  disturbing  to  the  individual. 

Labyrinthine  vertigo,  therefore,  is  a  false  sensation  of  motion 
similar  to  the  visual  illusion  of  motion  observed  when  watching  a 
moving  train  from  the  window  of  a  stationary  coach,  both  being 
unavoidable  phenomena  of  normal  special  sense  mechanisms,  which, 
however,  the  subject  easily  learns  to  interpret  and  disregard. 

One  must  not  fall  into  the  error,  however,  of  thinking  that  the 
lack  of  a  normal  ear  mechanism  would  be  advantageous  to  the  flier, 
because  of  the  immunity  of  vertigo  which  this  condition  would  con- 
fer. The  absence  of  such  an  essential  organ  as  a  motion-perceiving 
apparatus  is  too  great  a  handicap  to  the  man  traveling  in  an  "  air 
medium  "  even  to  think  for  a  moment  that  he  could  dispense  with  it 
for  the  sole  benefit  of  a  vertigo  immunity,  especially  since  the  normal 
individual  can  acquire  such  an  immunity  without  much  difficulty. 

VERTIGO  EFFECTS  OF  EAR  STIMULATION. 

1.  There  are  three  cardinal  planes  of  vertigo — horizontal,  frontal, 
and  sagittal. 


s 

2.  A  sense  of  being  turned  in  a  horizontal  plane — ^horizontal  ver- 
tigo— is  less  disturbing  than  a  sense  of  being  whirled  in  a  vertical 
plane — vertical  vertigo.  Each  semicircular  canal,  if  stimulated,  pro- 
duces a  vertigo  in  its  own  plane.  Therefore,  with  the  individual  in 
an  upright  position,  stimulation  of  the  horizontal  canal  is  much  less 
disturbing  than  stimulation  of  the  vertical  canals. 

3.  When  a  disturbing  or  disabling  vertigo  is  induced  in  the  vertical 
ir^emicircular  canals  the  effect  can  be  greatly  ameliorated  by  bringing 
the  vertical  canals  in  a  horizontal  position  or  plane,  which  can  readily 
be  done  by  bringing  the  head  forward. 

4.  All  types  of  vertigo,  no  matter  how  induced,  are  made  less  and 
less  disturbing  by  continual  repetition. 

PRACTICAL  APPLICATION  OF  VERTIGO  STUDY  TO  STUNT  FLYING. 

Let  us  consider  how  the  knowledge  of  the  various  effects  of  vertigo 
gained  in  the  laboratory  can  be  correlated  and  applied  to  various 
stunts. 


TIGHT  SPIRAL. 


iaf4 


TIGHT  SPIRAL. 


TIGHT  SPIRAL. 


TIGHT  SPIRAL. 


"  LOOPIMG." 
Arrow  indicates   plane  of  vertigo. 


"  LOOPING." 
Circles  indicate  plane  of  vertigo — sagittal  first,   then  frontal. 


131-2 


AIE  SERVICE  MEDICAL.  261 

SPINNING  NOSE  DIVE. 

In  this  maneuver  the  aviator,  face  downward,  is  whirled  about  an 
axis  with  his  head  and  body  practically  parallel  to  the  ground,  as 
shown  in  the  accompanying  sketch.  In  this  position  there  is  a  stimu- 
lation of  the  vertical  semicircular  canals  in  a  frontal  plane,  corre- 
sponding to  turning  in  the  chair  in  the  position  shown  below. 

When  he  "  comes  out "  of  the  spin,  the  pjane  of  vertigo,  which  until 
now  has  been  parallel  to  the  ground,  becomes  vertical  in  a  frontal 
plane,  i.  e.,  from  side  to  side,  so  that  instead  of  feeling  that  he  is 
turning  horizontally,  he  feels  that  he  is  whirled  in  an  up  and  down 
plane;  this  being  very  disturbing,  he  is  apt  to  lose  himself  momen- 
tarily and  attempt  to  correct  this  illusionary  movement  and  so  throw 
himself  into  another  spinning  nose  dive  in  the  opposite  direction. 
AVhen  this  same  experiment  is  carried  out  in  the  chair,  i.  e.,  when  he  is 
turned  with  his  head  forward,  simulating  his  position  during  this 
spinning  nose  dive,  and  attempts  to  sit  erect,  he  similarly  changes  his 
horizontal  vertigo,  with  which  he  started,  into  a  sensation  of  whirling 
in  an  up  and  down  plane.  In  attempting  to  correct  this  false  impres- 
sion he  throws  his  bodv  to  one  side  with  such  violence  that  unless 
caught  by  the  examiner  he  would  fall  to  the  floor.  It  is  easy  to  im- 
agine what  havoc  would  be  raised  with  the  controls  of  an  airship 
under  similar  conditions.  The  obvious  remedy  in  both  cases  is  to 
keep  the  head  down,  as  it  was  in  the  beginning,  so  that  the  vertigo  re- 
mains in  the  horizontal  plane. 

TIGHT   SPIRAL. 

In  this  maneuver  the  aviator  is  whirled  about  an  axis  with  his 
head  and  body  practically  parallel  with  the  ground  but  facing  the 
horizon.  The  stimulation  occurs  in  the  vertical  canals  but  in  a 
plane  practicallj^  parallel  with  the  ground  as  long  as  the  spiral  lasts. 
When  he  comes  out,  however,  the  plane  of  vertigo,  horizontal  until 
now,  becomes  vertical  in  a  sagittal  (from  before  backward)  plane, 
so  that  he  feels  himself  pitching  forward  or  backward  and  may 
again  meet  with  disaster  in  attempting  to  correct  for  this  illusion. 

In  the  turning-chair  this  maneuver  can  be  simulated  by  turning 
the  individual  with  his  head  sharply  inclined  over  the  shoulder  as 
illustrated. 

The  obvious  remedy  for  the  aviator  in  this  case  is  to  tilt  his  head 
sharply  to  one  side  when  coming  out  of  the  spiral,  since  by  so  doing 
he  will  prevent  the  vertigo  from  assuming  an  up  and  down  whirl. 

LOOP. 

In  this  stunt,  as  shown  in  the  accompanjdng  sketch,  the  vertical 
canals  are  stimulated  in  the  saggittal  plane  (as  in  the  spiral,  but  to 
a  lesser  degree).  The  correction  is  accomplished  by  tilting  the  head 
sharply  over  one  shoulder. 


262  AIR  SERVICE  MEDICAL. 

IMMELMANN   TURN. 

In  this  evolution,  as  shown  in  the  foregoing  sketches,  we  have  a  com- 
pound maneuver.  During  the  first  or  loop  portion  the  vertical  canals 
are  stimulated  in  the  sagittal  plane,  followed  in  the  second  part  of 
the  stunt  by  a  stimulation  of  the  vertical  canals  in  the  frontal  plane. 
The  effect  of  the  first  portion  is  lost  during  the  remainder  of  the 
stunt  so  that  on  emerging  the  aviator  has  only  to  deal  with  the  ver- 
tigo induced  by  the  last  part,  namely  vertigo  in  the  frontal  plane. 
The  obvious  correction  is  to  throw  the  head  forward  while  "  coming 
out."  In  a  similar  manner  the  vertigo  induced  by  the  "  barrel  roll," 
"  falling  leaf,"  "  wing  over,"  and  other  stunts  can  be  readily  analyzed. 

It  is,  of  course,  true  that  the  experienced  stunt  flier  is  not,  as  a  rule, 
upset  by  the  vertigo  induced  by  these  stunts  because  of  the  many 
hours  of  practice  he  has  had,  but  no  matter  how  well  trained  and 
experienced  he  may  be  he  may  occasionally  find  himself,  especially 
in  actual  combat,  doing  more  whirling  and  at  a  greater  rate  of  speed 
than  his  training  has  prepared  him  for,  and  an  understanding  of 
these  principles  might  be  the  means  of  saving  his  life.  As  a  matter 
of  fact,  stunt  fliers  develop  instinctively  certain  maneuvers  which 
neutralize  the  disabling  effects  of  vertigo;  thus  one  flier  found  by 
practical  experience  that  by  leaning  as  far  forward  as  possible,  so 
that  his  head  was  practically  inverted,  a  spinning  nose  dive  gave  him 
practically  no  disabling  vertigo.  Another  found  that  going  into  a 
straight  nose  dive  immediately  following  a  spinning  nose  dive  saved 
him  from  any  uncomfortable  dizziness. 

These  fliers  have  instinctively  adopted  means  which  at  all  times 
kept  the  vertigo  in  a  horizontal  plane — procedures  based  on  sound 
otologic  principles.  Experienced  aviators,  on  being  put  through  the 
various  stunts  in  the  laboratory,  when  shown  how  easily  the  effects 
of  vertigo  are  neutralized  by  certain  changes  in  the  position  of  the 
head,  are  of  the  unanimous  opinion  that  such  knowledge  is  of  the 
greatest  practical  value,  especially  in  stunting.  It  is  obvious  that 
to  the  less  experienced  this  knowledge  is  of  even  greater  importance. 

The  greatest  usefulness  of  the  knowledge  that  "  stunting "  is  an 
ear  problem  lies  in  the  fact  that  the  flier  may  be  educated  to  disre- 
gard the  vertigo  effects  of  his  stunts  in  the  laboratory  instead  of 
among  the  clouds,  and  without  danger,  acquire  a  tolerance  to  evolu- 
tions to  a  degree  impossible  in  the  air.  This  can  be  accomplished 
by  the  use  of  an  otologic  apparatus  known  as  the  Orient ator.  In  its 
construction  it  is  like  the  cockpit  of  an  aeroplane  suspended  in  con- 
centric rings  after  the  manner  of  a  ship's  compass.  The  move- 
ments (or  changes  of  position)  which  are  possible  in  all  directions 
except  actual  forward  progression  are  governed  by  the  individual 
seated  in  the  machine  using  a  set  of  controls  resembling  those  of  an 


"  RUGGLES    ORIENTATOR." 

(Supplied  thniiigli  tlu"  courtesy  of  the  Naval  Consulting  Boarcl.) 


132-1 


"  RUGGLES    ORIENTATOR." 
(Supplied  through  the  courtesy  of  the  Naval  Consulting  Board.) 


132-2 


"  RUGGLES    ORIENTATOR." 
(Supplied  through  the  courtesy  of  the  Naval  Consulting  Board.) 


132   3 


"  RUGGLES    ORIENTATOR.' 

(Supplied  through  the  courtesy  of  the  Navnl  Consulting  Boiird.) 


132-4 


"KUGGLES  ORIENTATOR." 
(Supplied  through  through  the  courtesy  of  the  Naval  Consulting  Board.) 


AIR  SERVICE   MEDICAL.  263 

aeroplane.  Strapped  in  this  machine  he  is  enabled  to  execute  any 
evolution,  such  as  the  loop,  spiral,  etc.,  at  any  desired  rate  of  speed 
for  any  number  of  turns  and  thus  acquire  in  absolute  safety  a  toler- 
ance for  the  disturbing  effects  of  vertigo  induced  by  these  evolutions 
instead  of  acquiring  this  tolerance  and  knowledge  by  actual  flying 
with  its  consequent  crashes  and  possible  loss  of  life.  In  addition,  it 
will  enable  him  to  adapt  himself  to  new  and  most  unusual  conditions. 
He  will  learn  to  orientate  himself  in  hew  and  rapidly  changing 
positions  of  the  body  and  to  perform  properly  the  complicated  acts 
necessary  to  control  an  aeroplane  while  flying  with  his  head  down, 
etc.,  which  entails  an  entirely  reversed  relation  to  external  objects,  a 
condition  in  itself  most  disturbing  and  pregnant  with  possibilities  of 
disaster. 

The  orientator  placed  in  the  ground-  and  flying-  schools  will  save 
many  lives  and  machines,  shorten  materially  the  time  of  flying  in- 
struction, and  develop  a  large  number  of  stunt  fliers. 

v.— THE  MANUAL  OF  THE  OPHTHALMOLOGICAL  DEPARTMENT 

RESEARCH  LABORATORY. 

THE  SELECTION  OF  THE  AVIATOR. 

In  answer  to  the  first  call  for  fliers  approximately  100,000  men,  the 
pick  of  the  youth  of  this  country,  applied  for  service  in  the  Aviation 
Section,  Signal  Corps,  United  States  Army.  Due  to  the  genius  for 
organization  and  tireless  energy  of  the  medical  officers  of  the  Regular 
Army,  these  men  were  carefully  examined  by  500  physicians,  work- 
ing in  67  examining  units,  and  a  sufficient  number  were  selected. 

It  is  safe  to  say  that  these  men,  by  reason  of  this  careful  method  of 
selection,  are  physically  fit,  and  it  is  well  that  this  is  the  case,  for  an 
aviator  must  not  only  be  physically  perfect  to  begin  with,  but  also 
be  kept  in  training.  It  is  certainly  more  important  to  have  an  aviator 
in  perfect  physical  condition  than  a  football  player.  Every  flier 
should  be  under  the  care  of  a  medical  man  thoroughly  trained  in  the 
care  of  the  aviator  and  the  symptoms  and  dangers  of  the  lack  of 
oxygen. 

If  we  study  for  a  moment  the  routine  employed  in  the  examination 
of  the  eye  we  will  easily  see  that  any  man  who  could  pass  these  tests 
must  have  eyes  as  nearly  perfect  as  nature  permits. 

PHYSICAL  EXAMINATION  OP  APPLICANTS  FOR  DETAIL  IN  THE  DEPARTJIENT 

OF  MILITARY  AERONAUTICS. 

I.  History. — Question  the  candidate  carefully  concerning  previous 
or  present  eye  trouble,  use  of  glasses,  lachrymation,  photophobia,  and 
diplopia.  If  glasses  are  worn,  symptoms  when  not  wearing  correct- 
ing lenses. 


264  AIE  SERVICE   MEDICAL. 

II.  Stereoscopic  vision. — The  ability  to  appreciate  depth  and  dis- 
tances by  means  of  binocular  vision.  The  ordinary  stereoscope  may 
be  used.  The  cards  should  be  clean  and  flat.  The  candidate  should 
have  a  good  light  coming  over  the  shoulder  directly  on  the  card. 
The  card  should  be  moved  back  and  forth  until  the  point  of  greatest 
distinctness  is  attained.  Have  the  candidate  name  the  sequence  of 
objects  from  before  backward,  as  he  .^ees  them  through  the  stereoscope. 
This  should  be  done  readily  and  without  error,  keeping  in  mind  the 
fact  that  even  though  the  usual  order  of  seeing  the  objects  on  the 
original  card  is  9-1-7,  3-2-4,  5-6-8,  and  10,  the  confusion  of  4  and  5, 
9  and  1,  and  8  and  10  occurs  in  people  with  normal  stereoscopic  vision. 
In  case  of  doubt,  use  in  addition  the  smaller  objects  on  individual 
pictures,  e.  g.,  on  No.  9  from  before  backward  is  seen  cross,  balloon, 
and  flag;  No.  8,  balloon,  cross,  rod,  and  pennant;  No.  10,  pennant, 
balloon,  and  cross.  Inability  to  stereoscope  properly  is  a  cause  for 
rejection, 

III.  Ocular  movements. — These  are  tested  roughly  by  requiring 
both  eyes  of  the  candidate  to  be  fixed  on  the  examiner's  finger,  which 
is  carried  from  directly  in  front  of  the  eyes  to  the  right,  to  the  left, 
up  and  down.     The  ocular  movements  must  be  regular  and  identical. 

IV.  Pupillary  reactions. — These  should  be  regular  and  equal  when 
responding  to  (1)  direct,  (2)  indirect  light  stimulation,  and  (3) 
to  accommodation.  Face  the  candidate,  Avho  should  be  looking  into 
the  distance,  and  place  a  card  as  a  screen  before  both  eyes.  Uncover 
one  eye  after  a  short  interval  and  allow  bright  daylight  to  shine  into 
this  eye.  The  resulting  contraction  of  the  iris  of  this  eye  is  called  a 
direct  reaction.  Eepeat  the  test,  but  now  observe  the  iris  of  the 
shaded  e3'e.  If  this  iris  contracts,  it  is  termed  the  indirect  or  con- 
sensual reaction.  Repeat  tests  on  the  other  eye.  With  both  the  candi- 
date's eyes  open  and  uncovered,  have  him  fix  on  a  distant  object,  then 
focus  on  a  pencil  point  held  approximately  10  centimeters  in  front 
of  the  eyes.  Both  irides  should  contract,  which  is  called  the  reaction 
to  accommodation. 

V.  External  ocular  examination. — Place  the  candidate  facing  a 
good  light  and  examine  each  eye  carefully  with  the  aid  of  a  hand 
lens,  noting  any  abnormality.  The  eye  should  be  free  from  disease, 
congenital  or  acquired,  such  as  lesions  of  the  cornea,  iris,  or  lens, 
including  affections  of  the  surrounding  structures,  such  as  patho- 
logical conditions  of  the  lachrymal  apparatus,  conjunctival  deformi- 
ties, or  any  affection  which  would  tend  to  cause  blurring  of  vision 
if  the  eyes,  unprotected  by  glasses,  were  exposed  to  wind  or  other 
unfavorable  atmospheric  conditions. 

VI.  Ocular  nystagmus. — If  it  occurs  on  looking  straight  ahead 
or  laterally,  40°  or  less,  it  is  a  cause  for  rejection. 


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AEB  SEEVIOE  MEDICAL.  265 

(a)  Spontaneous  ocular  nystagmus  produced  by  extreme  lateral 
rotation  of  the  eyes,  50°  or  more,  is  not  a  cause  for  rejection,  as 
it  is  found  in  the  normal  individual.  It  is  usually  manifested  by 
a  few  oscillating  movements,  never  rotary,  which  appear  when  the 
eyes  are  first  fixed  in  extreme  lateral  positions.  Select  a  scleral 
vessel  near  the  corneal  margin  as  a  point  for  observation. 

VII.  Field  of  vision. — The  confrontation  test  mny  be  used  to  de- 
termine roughly  the  limits  of  the  visual  field.  The  field  is  tested 
separately  for  each  eye.  Place  the  candidate  with  his  back  to  the 
source  of  light  and  have  him  fix  the  eye  under  examination  (the  other 
eye  being  covered)  upon  the  examiner's,  which  is  directly  opposite 
at  a  distance  of  2  feet.  For  example:  The  candidate's  right  eye 
being  fixed  upon  the  examiner's  left  eye;  the  examiner  then  moves 
his  fingers  in  various  directions  in  a  plane  midway  between  himself 
and  the  candidate,  until  the  limits  of  indirect  vision  are  reached. 
The  examiner  thus  compares  the "  candidate's  field  of  vision  to  his 
own,  and  can  thus  roughly  estimate  whether  normal  or  not.  A  re- 
stricted field  of  vision  or  marked  scotoma  should  be  confirmed  by 
the  use  of  a  perimeter,  as  it  would  be  a  cause  for  rejection. 

VIII.  Color  vision. — Should  be  normal.  A  Jennings  test  is  re- 
quired. If  confusion,  the  eyes  should  be  tested  with  a  Williams 
lantern.  The  Jennings  blank,  properly  filled  out,  should  form  a  part 
of  the  physical  record.  If  the  candidate  is  suspected  of  having 
learned  the  Jennings  test,  the  card  and  blank  may  be  turned  over 
and  punched  from  the  unfinished  side. 

IX.  Muscle  balance  at  20  feet. — A  phorometer,  with  spirit  level  or 
maddox  rod  and  rotary  prism  attached,  should  be  used.  Muscle  bal- 
ance is  satisfactory^,  provided  there  is  not  more  than  1  degree  of 
hyperphoria,  2  degrees  of  exophoria,  or  6  degrees  of  esophoria  (if 
in  this  latter  case  there  is  a  prism  divergence  or  abduction  of  not  less 
than  6  degrees).  In  all  cases  of  heterophoria  the  duction  powe]-  of 
the  muscles  must  be  taken  d^id  recorded. 

{a)  The  screen  and  parallax  test:  In  case  the  above-described 
apparatus  is  not  available,  the  following  method  may  be  used  until 
the  proper  instruments  are  obtained : 

The  candidate  is  seated  6  meters  from  a  5-millimeter  light  on  a 
black  field  or  a  1  centimeter  black  dot  on  a  white  field,  which  he  fixes 
intently.  Shift  a  small  card  quickly  from  eye  to  eye  and  note  any 
movement  of  the  eye  as  it  is  imcovered  and  ask  the  candidate  to  de- 
scribe any  movement  of  the  eye  or  the  light.  Orthophoria  obtains 
if  there  is  no  apparent  movement  of  the  eye  or  the  light.  Movement 
of  the  test  object  or  eye  with  the  card  signifies  exophoria,  against  the 
card,  esophoria,  and  vertical  movement  hyperphoria.  Prisms  are 
placed  with  the  base  in  for  exophoria,  out  in  esophoria  and  up  or 


266  •  AIR  SERVICE  MEDICAL. 

down  in  hyperphoria,  until  the  test  object  and  the  eye  just  begin  to 
mo\  e  in  the  opposite  direction.  The  weakest  prism  which  causes  re- 
versal of  the  movement,  minus  2  prism  degrees,  is  the  measure  of 
the  heterophoria.  If  there  are  less  than  5  degrees  of  heterophoria, 
only  1  prism  degree  is  subtracted. 

(b)  Near  point  of  convergence:  A  2-millimeter  white-headed  pin 
or  a  1-millimeter  black  dot  on  a  white  card  is  carried  toward  the 
subject  along  a  millimeter  rule  from  a  distance  of  50  centimeters,  and 
the  point  noted  at  which  one  or  both  eyes  cease  to  fix  or  diplopia  is 
first  noted  by  the  candidate.  This  point  is  measured  in  millimeters 
from  the  anterior  surface  of  the  cornea.  Keep  the  test  object  in  the 
mid  line,  a  few  degrees  below  the  horizontal  plane.  A  near  point 
greater  than  65  millimeters  at  25  years  of  age,  and  85  millimeters  at 
30  years  of  age  is  a  cause  for  disqualification. 

X.  Visual  acuity. —  (a)  Acuity  for  distance:  Test  each  eye  sepa- 
rately, 20  feet  from  a  well-illuminated  card  with  Snellen  letters. 
Full  twenty  twentieths  vision  in  each  eye  is  desired,  but  a  candidate 
may  be  allowed  to  miss  three  letters  on  the  20/20  line  with  one  eye, 
provided  the  other  has  full  20/20  vision,  and  all  other  tests  are  nor- 
mal. Visual  acuity  should  be  taken  without  the  use  of  correcting 
lenses. 

Place  a  plus  2.00D  sph.  before  each  eye  successively  while  the  other 
eye  is  covered,  A  candidate  who  can  still  read  20/20  with  either  eye 
is  disqualified. 

(5)  Near  point,  or  acuity  for  near  vision  is  determined  separately 
for  each  eye  by  requiring  the  candidate  to  read,  in  a  good  light, 
Jaeger  test  type  No.  1,  gradually  bringing  the  card  toward  the  un- 
covered eye  until  the  first  blurring  of  the  print  is  noted. 

The  distance  of  this  point  from  the  anterior  siirface  of  the  cornea, 
measured  in  centimeters,  is  the  near  point.  A  distance  greater  than 
11  centimeters  at  19  years  of  age,  greater  than  13  centimeters  at  25 
years  of  age,  or  greater  than  15  centimeters  at  30  years  of  age,  dis- 
qualifies. 

XI.  Ophthalmoscopic  findings. — Drop  one  drop  of  a  5  per  cent 
solution  of  euphthalmin  in  each  eye.  Have  the  candidate  keep  his 
eyes  closed.  After  15  minutes  repeat  the  drops,  then  examine  15 
minutes  later.  A  solution  of  cocaine,  4  per  cent,  may  be  substituted, 
cautioning  the  candidate  to  keep  his  eyes  closed  between  installa- 
tions. A  pathological  condition  of  the  fundus,  active  or  quiescent, 
is  a  cause  for  rejection. 

VALUE  or  THE  EYE  IN   AVIATION, 

I.  Judgment  of  distance. — Judgment  of  distance  is  assisted  by  the 
power  of  stereoscopic  vision,  and  for  this  reason  the  eyes  of  all 
candidates  for  admission  into  the  Aviation  Section,  Signal  Corps 


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ATR  SETIVTCE  IVIEDTOAL.  267 

of  the  United  States  Army,  have  had  their  binocular  vision  tested  by 
means  of  a  stereoscope.  Inability  to  stereoscope  quickly  and  accu- 
rately is  considered  a  cause  for  disqualification.  We  know  that  if  a 
man  loses  one  eye  he  is  often  able  to  judge  distance  very  accurately 
with  the  remaining  one,  but  it  requires  time  for  him  to  develop  this 
power.  It  would  therefore  seem  logical,  at  least  while  we  are  able 
to  select  our  men  carefully,  to  accept  only  those  with  normal  stereo- 
scopic vision. 

Speaking  of  error  of  judgment  in  flying  as  a  cause  of  aeroplane 
accidents,  Anderson  states  that  this  error  may  occur  in  getting  off 
the  ground,  in  the  air,  or  when  landing.  Of  the  58  crashes  in  the 
"'  V  "  series,  this  cause  accounted  for  42 — 4  in  getting  off  the  gi'ound 
and  38  in  landing. 

Of  the  many  examples  of  error  in  judgment  in  flying,  perhaps 
the  commonest  is  when,  on  landing,  the  pupil  misjudges  his  distance 
from  the  ground  and  either  flattens  out  too  soon  and  "pancakes," 
with  a  possible  crash,  depending  on  the  height,  or  else  flattens  out 
too  late  and  strikes  the  ground  at  a  great  angle,  usually  overturning 
and  wrecking  the  machine. 

It  is  difficult  to  estimate  and  account  for  these  errors  of  judgment. 
In  some  cases  it  may  be  due  to  insufficient  instruction.  In  other 
cases,  even  after  prolonged  instruction,  the  pupil  may  still  misjudge 
distance,  and  on  examination  one  occasionally  finds  that  his  standard 
of  vision  is  below  normal;  but,  on  the  other  hand,  he  may  be  found 
physically  fit,  with  normal  vision  and  normal  muscle  balance.  In 
the  latter  case  Anderson  believes  it  may  be  a  question  of  delayed 
reaction  time,  and  especially  the  visual  reaction  time,  upon  which 
the  aviator  is  so  much  dependent.  Normally  this  reaction  time  is 
nineteen  one-hundredths  or  twenty  one-hundredths  of  a  second.  It 
may  be  delayed  by  fatigue  and  excesses,  but  in  some  individuals  who 
are  otherwise  physically  fit  it  is  found  to  be  much  slower  than  iu 
others. 

Hence,  in  the  selecting  of  candidates  for  aviation  the  visual  and 
other  reaction  times  should  be  normal.  By  the  French  medical  au- 
thorities on  aviation  candidates  are  rejected  if  simple  reaction  times 
are  found  to  be  of  the  delayed  type.  The  Italians  also  seem  to  lay 
considerable  stress  upon  simple  reaction  time.  The  men  who  have 
done  the  most  work  in  reaction  time  in  this  country,  are  of  the 
opinion  that  simple  reaction  time  is  of  little  value  in  the  selection  of 
candidates  for  aviation.  The  accurate  determination  of  the  visual 
discrimination  reaction  time  and  other  complex  reaction  times  might 
be  of  considerable  value.  It  would  seem  as  though  physical  condition 
on  a  given  day  and  the  added  strain  of  low  oxygen  tension  should  be 
taken  into  consideration  in  seeking  the  cause  of  these  accidents.  We 
know  that  there  might  be  a  temporary  visual  disturbance  or  weaken- 


268  AIE  SEKVIOE  MEDICAL. 

ing  of  the  external  ocular  muscles,  and  this  might  account  for  some 
of  the  accidents.  Naturally,  examination  of  the  eyes  later  on  might 
show  nothing. 

II.  Normal  visual  acuity. — As  long  as  we  can  in  this  country  selecl 
only  those  men  with  practically  perfect  vision  it  would  seem  well 
to  do  this.  A  man  with  poor  vision  will  not  be  able  to  see  an  enemy 
plane  as  soon  as  a  man  with  perfect  vision.  He  will  not  be  able  to 
accurately  differentiate  objects  seen  from  the  air  in  selecting  a  land- 
ing place,  and  when  he  has  reached  the  ground  he  will  not  see  ob- 
structions in  his  path  as  clearly  as  he  should.  The  latter  may  result 
in  the  plane  being  "nosed  over."  In  a  recent  discussion  of  the 
"  Physical  Qualities  of  Aviators  "  all  the  British  officers  and  physi- 
cians taking  part  agreed  that  the  factor  of  vision  was  of  the  greatest 
importance,  and  Clark  pled  for  the  use  of  a  cycloplegic  in  making 
examinations  for  admission  to  the  flying  corps.  During  the  low 
oxygen  tension  test  visual  acuity  diminished  in  28  per  cent  of  the 
normal  men  examined  and  in  37.5  per  cent  of  the  men  who  were 
ocularly  disqualified  for  flying. 

III.  Normal  color  vision. — It  is  important  that  the  flier  have  nor- 
mal color  vision  in  order  that  he  may  accurately  determine  the 
markings  of  the  different  planes,  differentiate  between  signal  lights, 
and  in  helping  him  to  make  landings  at  night.  During  the  day  the 
discrimination  between  the  color  of  a  building,  field,  forest,  or  swamp 
is  essential  in  selecting  a  landing  place.  There  has  been  no  change 
in  color  vision  during  the  rebreathing  test  or  in  the  low-pressure 
chamber. 

IV.  Field  of  hinocular  fixation. — It  is  important  that  the  aviator 
be  able  to  carry  the  eyes  as  far  as  possible  in  various  directions 
without  turning  his  head  and  without  seeing  double.  If  a  man  has 
a  contracted  binocular  field  of  vision,  it  certainly  impairs  his  effi- 
ciency, whether  observing,  fighting,  or  flying.  In  50  per  cent  of 
the  subnormal  men  examined  during  the  low  oxygen  tension  test  we 
have  found  contraction  of  the  field  of  binocular  fixation,  the  con- 
traction being  most  marked  in  the  upper  field. 

V.  Muscle  balance. — Normal  muscle  balance  should  be  insisted 
upon,  for  even  a  small  defect  may  be  accentuated  by  the  strain  of 
flying  and  lack  of  oxygen  and  result  in  diplopia  or  at  least  a  marked 
contraction  of  the  field  of  binocular  vision  at  low  altitudes.  Ex- 
ophoria  and  hyperphoria  have  been  shown  to  be  the  most  important, 
due  to  the  fact  that  the  weakness  of  the  ocular  muscles  caused  by 
the  lack  of  oxygen  produces  diplopia  more  readily  in  exophoria  and 
hyperphoria  than  in  esophoria. 

VI.  Field  of  vision. — The  field  of  vision  should  be  normal,  as  the 
aviator's  safety  depends  to  a  great  extent  upon  his  ability  to  detect 


170 

Lieul.  Thomas,  Francis  W. 

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269 


enemy  planes  or  in  training  his  own  plane  in  the  various  fields  while 
liis  gaze  is  fixed  straight  ahead.  The  aeroplane  and  the  goggle  also 
do  harm  in  that  they  restrict  the  field  of  vision,  and  many  accidents 
lesult  from  this.  Everything  should  be  done  to  improve  the  con- 
struction of  goggles  and  planes  so  that  the  visual  field  will  be  re- 
stricted as  little  as  possible. 

VII.  The  'percejHion  of  motion  and  its  direction. — The  perceptior 
of  motion  and  its  direction  is  of  gi'eat  importance  to  the  aviato^". 
Appropriate  tests  for  measuring  this  have  been  devised.  The  best 
pilots  say  that  they  finally  develop  the  power  to  use  the  peripher} 
of  the  retina  so  that  it  is  of  greater  value  in  detecting  enemy  planes 


I.  ..t  p 


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VIII.  The  importance  of  the  eye  in  maintaining  equilibrium. — 
ik^fore  going  into  this,  first  let  it  be  stated  that  the  subject  of  equi- 
libratix)n  is  a  complex  one  and  that  those  of  us  who  have  an  interest 
in  it  from  a  practical  standpoint  appreciate  the  difficulty  of  the 
subject  and  realize  that  although  the  aviator  may  fly  when  one  part 
of  this  mechanism  is  deranged  or  destroyed,  we  believe  that  in  select- 
ing men  for  flying  positions  that  it  is  well  to  make  sure  that  all  the 
senses  used  in  this  complex  act  are  normal.  The  most  important 
factors  in  receiving  impressions  are  deep  sensibility,  tactile  sense,  the 


270  AIR  SERVICE  MEDICAL. 

vestibular  apparatus,  and  the  eyes.  The  central  nervous  system  con- 
nections must  functionate  perfectly  to  use  the  information  it  receives 
to  the  best  advantage.  Finally,  the  muscles  should  be  in  condition 
to  carry  out  the  commands  of  the  central  nervous  system. 

That  many  aviators  depend  largely  upon  their  visual  impressions 
in  the  maintenance  of  equilibrium  is  evidenced  by  the  fact  that  they 
often  tie  a  piece  of  string  as  a  streamer  to  one  of  the  forward  struts, 
so  that  they  may  more  readily  note  the  first  evidence  of  a  side  slip 
when  they  are  flying  in  a  cloud.  In  spite  of  the  fact  that  we  miss  the 
visual  impressions  when  they  are  not  received,  we  are  still  able  to 
control  the  plane  if  the  remainder  of  the  balance  mechanism  is 
functioning  normally. 

IX.  Retinal  sensitivity  to  light. — It  is  important  that  the  retina 
be  sensitive  to  light  impressions,  especially  for  those  men  who  are 
carrying  out  night  bombing  expeditions.  With  this  in  mind,  most 
of  the  allied  nations  require  special  tests  for  retinal  sensitivity.  A 
test  of  the  contrast  sensitivity  of  the  retina  is  believed  to  be  the  most 
useful  for  our  work,  and  only  men  who  have  normal  sensitivity  in 
this  respect  will  be  selected  for  night  flying. 

THE  CARE  OF  THE  FLIER  AND  THE  EFFECT  OF  ALTITUDE  AND  THE  STRATN 

OF  FLYING  ON   THE  EYE. 

Even  though  our  aviators  have  been  examined  with  the  greatest 
care  and  their  eyes  are  as  nearly  perfect  as  nature  permits,  the  adapt- 
ing mechanism  of  the  human  machine,  including  the  eye,  was  de- 
signed for  use  on  earth,  and  altitude  adds  an  unusual  strain.  Medi- 
cal men  agree  that  definite  physiologic  changes  occur  in  man  living 
at  high  altitudes  which  permit  them  to  withstand  lack  of  oxygen, 
but  they  believe  from  the  examinations  that  have  been  made  of  fliers 
that  they  do  not  become  acclimated,  but  often  show  rather  rapid 
physical  deterioration. 

The  most  important  ocular  symptom  is  failing  vision.  The  pilot 
complains  that  he  can  not  see  the  ground  clearly  in  landing  and  has 
difficulty  in  picking  out  enemy  planes.  There  may  be  no  defect  in 
vision,  but  there  is  usually  some  slight  error  which  was  previously 
correctable  by  an  unconscious  muscular  effort.  The  muscles  become 
fatigued,  due  to  the  strain  of  flying,  and  the  defect  shows  itself.  A 
few  days'  rest  has  been  sufficient  in  the  few  cases  Maj.  James  L.  Bir- 
ley,  R.  A.  M.  C,  has  seen,  to  restore  normal  vision. 

Certain  individuals  with  apparent  perfect  acuity  of  vision  are 
ocularly  weak  in  that  they  are  unable  to  make  use  of  both  eyes,  due 
to  some  defect  in  binocular  vision  or  fusion  sense.  This  interferes 
somewhat  with  judgment  of  distance,  and  the  disability  tends  to 
increase  under  the  strain  of  aviation  and  lack  of  oxygen,  resulting  in 


JOHNSON  VISUAL  ACUITY  TESTINiJ   AITAItA  TUS. 


Lieut.  Johnson's  visual  acuity  test  with  subjer^t  on  rebreathing  apparatus. 
Ox.vgen  at  end  of  exiierinieiit,  lOVr.  Lower  jiarts  of  curve  indicate  maximal 
vision.  Subject  observes  test  object  for  periods  of  three  minutes,  with  one 
minute    intervals   of  rest. 


Test  object  observed  during  periods  of  three  minutes  with  one  minute  intervals 
of  rest.  Amyl  nitrite  (2  minims)  iidialed  during  third  period.  Lower  ex- 
cursions of  curve  indicate  clearer  vision. 


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CADET  D.  VV.  MILLS,  5/9/18. 


to 


141 


AIR  SERVICE  MEDICAL.  271 

bad  landings,  "  crashes,"  and  consequent  loss  of  personnel  and  mate- 
rial.   These  conditions  may  often  be  improved  by  treatment. 

Irritation,  congestion,  and  inflammation  of  the  conjunctiva  and 
epiphora  were  common  complaints  of  the  fliers  at  Chanute  Field. 
Most  aviators  realize  the  necessity  for  wearing  goggles,  but  many  of 
them  fit  poorly,  allowing  the  cold  air  to  strike  the  eye  with  great 
force,  most  often  near  the  internal  canthus  where  the  lachrymal 
puncta  are  situated.  This  probably  accoufits  for  the  disagreeable 
symptoms  noted.  The  remedy  is  found  in  the  wearing  of  properly 
fitted  goggles  and  the  use  two  or  three  times  daily  of  a  2  per  cent 
boric  acid  solution  containing  1  grain  of  zinc  sulphate  to  the  ounce. 
In  some  instances  1  grain  of  cocaine  and  10  to  30  minims  of  1-to- 
1,000  adrenalin  cliloride  may  be  added  to  the  ounce. 

GOGGLES. 

I.  The  glass — 

{a)  Should  have  an  optically  plane  surface. 

(&)  Should  have  a  light  transmission  of  90  per  cent  or  over  for 
plain  white  glass. 

(c)  If  a  colored  glass  is  desired,  Noviol  "  C,"  made  by  the  Corning 
Manufacturmg  Co.,  of  New  York,  with  a  light  transmission  of  87 
per  cent,  is  excellent.  Euphos  has  given  great  comfort  and  the  glass 
passes  a  good  test.  The  retina  of  the  eye  is  sensitive  to  the  glare,  and 
that  is  probably  one  of  the  causes  for  physical  fatigue  of  the  aviator. 
The  colored  lenses  shut  out  most  of  the  ultraviolet  rays,  and  some 
consider  them  of  great  value  in  bright  sunlight,  in  snow,  on  water, 
and  above  the  clouds.  Many  aviators  object  to  any  tint  in  their  lenses, 
due  to  the  fact  that  they  say  they  are  unable  to  see  as  well  in  a  fog 
and  that  the  color  in  the  lenses  changes  the  color  of  objects  looked 
at,  especially  the  Gennan  uniform  and  the  fields  in  making  landings, 
resulting  sometimes  in  the  selection  of  poor  landing  places  or  in  the 
misjudgment  of  distance. 

{d)  Thickness  of  the  glass:  The  lenses  should  be  2  or  3  millimeters 
thick. 

(e)  Many  aviators  insist  upon  some  form  of  so-called  nonbreak- 
able  glasses,  which  is  nothing  more  than  two  pieces  of  glass  with  a 
piece  of  celluloid  between.  This  piece  of  celluloid  cuts  down  the 
transmission  of  light  between  16  and  19  per  cent,  and  no  matter  how 
clear  the  celluloid  is  originally,  it  deteriorates  with  age  and  becomes 
yellow  and  less  transparent.  When  these  glasses  are  struck  with 
considerable  force  the  glass  on  the  posterior  surface  splinters  off  and 
flies  into  the  eye.  Even  with  these  disadvantages,  some  men  insist 
upon  the  nonbreakable  feature,  and  perhaps  not  without  reason,  for 
even  though  the  splinters  do  fly  off  the  back  of  the  glass,  the  eye 
closes  immediately  in  an  accident,  and  these  small  particles  would 


272  AIB  SEEVIOE  MEDICAL. 

hardly  penetrate  the  lids,  and  there  is  no  doubt  that  in  some  instances 
the  celluloid  prevents  the  driving  of  large  pieces  of  glass  toward 
the  eye. 

II.  Visual  field. — It  is  most  important  that  the  aviator  have  a 
broad  field  of  vision,  and  for  this  reason  a  large  curved  glass  is  desir- 
able. Without  a  broad  field  of  vision  the  aviator  may  not  see  one  of 
his  own  planes  in  time  to  prevent  an  accident.  Pilots  who  are  doing- 
actual  fighting  demand  a  broad  visual  field  above  everything  else. 

III.  Visual  acuity. — It  is  important  that  the  aviator  have  keen 
vision,  and  for  this  reason  glass  with  optically  plane  surfaces  should 
be  furnished  and  a  determination  made  of  hoAv  much  visual  acuity  is 
cut  down  by  celluloid. 

IV.  Safety  to  the  eye. — The  parts  of  the  goggle  which  come  in  con- 
tact with  the  brow,  nose,  and  cheeks  should  have  round  edges  and 
be  protected  by  a  soft  cushion. 

V.  Lightness  and  strength. — The  goggles  should  be  light,  so  that 
they  will  not  cause  discomfort.  They  should  be  simple  in  con- 
struction and  yet  strongly  made. 

VI.  Comfort. — The  goggles  should  not  press  upon  the  bridge  of 
the  nose  so  as  to  produce  pain,  and  the  elastic  which  holds  the 
goggles  in  place  should  not  be  drawn  too  tight.  An  adjustable  inter- 
pupillary  distance  might  be  valuable. 

VII.  Cleansing. — Goggles  should  be  easily  cleaned,  and  there 
should  be  no  place  for  vermin  to  hide. 

IX.  Protecting  sinuses. — There  should  be  sufficient  covering  in 
connection  with  the  goggles  to  protect  the  frontal  sinus.  Aviators 
often  complain  of  pain  in  this  region  when  it  is  left  exposed. 

X.  Ventilation. — The  goggles  should  be  carefully  adjusted  so  that 
there  are  no  leaks,  especiallj'  near  the  nose,  which  would  permit  the 
wind  to  strike  the  internal  canthi  directlv.  Most  of  the  aviators 
who  have  done  fighting  at  high  altitudes  believe  that  the  goggles 
should  be  equipped  with  some  indirect  method  of  ventilation. 

XL  Material  for  lenses. — Glass  is  best.  Celluloid  and  gelatin 
smear  too  easily'  and  celluloid  deteriorates  too  rapidly.  Mica  chips 
and  cracks. 

XII.  Noninflainmdble. — The  material  of  which  the  goggle  is 
composed  should  be  noninflammable  and  for  this  reason  any  wooly 
material  is  dangerous,  as  it  bums  readil3^  Incendiary  bullets  are 
now  being  used,  and  they  cause  great  damage  when  they  strike  a  gas 
tank. 

XIII.  To  further  prevent  injury  to  the  aviator,  all  parts  of  the 
fuselage  or  control  system  which  he  is  liable  to  strike  in  falling 
should  be  protected  by  pneumatic  cushions. 


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143 


ATE  SEBVIOE  MEDICAL.  273 

"  Doctors  and  profeesional  aviators  have  noticed  that  during  the 
ascent  respirations  become  more  rapid  and  the  heart  beats  faster 
up  to  an  altitude  of  1,500  meters.  At  this  altitude  the  vision  may 
become  less  clear,  although  a  French  observer  states  that  at  2,000 
meters  the  visual  acuity  usually  increases  by  a  third  by  reason  of  the 
congestion  of  all  the  organs  of  the  head  and  in  particular  of  the 
choroid  and  of  the  retina."  Visual  acuity  tests  carried  out  under 
low-oxygen  tension  on  the  rebreathing  apparatus  and  in  the  low- 
pressure  chamber  have  not  shown  any  marked  increase  in  vision. 
On  the  contrary,  the  improvement,  when  it  occurred,  has  usually 
been  slight,  but  more  often  the  vision  has  remained  unchanged  and 
in  a  few  cases  has  fallen  off  considerably. 

"  During  the  descent,  there  is  another  series  of  phenomena  which 
increases  as  one  approaches  the  ground.  It  is  first  the  sensation  of 
smarting  of  the  face  with  redness  and  very  high  color.  The  eyes 
sting  and  are  injected.  The  nostrils  are  moist  and  then  comes  a 
headache,  or  more  exactly  a  sort  of  heavy  feeling  in  the  head  with  a 
sensation  of  obstruction.  Swelling  in  the  pharynx  at  the  level  of 
the  larynx.    Finally  there  is  a  strong  tendency  to  sleep." 

"  To  explain  these  difficulties  during  the  descent,  one  may  admit 
that  an  airman  who  falls  to  the  earth  in  four  or  five  minutes  or 
less,  after  having  attained  3,000  or  4,000  meters  of  elevation  in  20 
minutes,  had  not  had  time  to  adapt  his  circulator}^  system  to  the 
different  barometric  pressures."  From  the  experimental  work  done, 
the  change  in  oxj'gen  tension  would  seem  to  be  the  most  important 
factor  in  the  production  of  symptoms. 

The  question  of  correcting  lenses  is  an  important  one  and  most 
ophthalmologists  feel  that  it  is  better  in  principle  not  to  have  vision 
corrected  by  lenses,  at  least  as  long  as  we  are  able  to  obtain  men 
with  nearly  perfect  vision.  The  aviator  needs  perfect  vision  and  a 
normal  ability  to  distinguish  colors,  a  rapid  valuation  of  distances 
and  the  faculty  of  accommodating  rapidly.  There  have  been  many 
accidents  described  as  due  to  hyperopia,  myopia,  and  astigmatism, 
and  it  is  a  question  if  it  would  not  be  well  to  use  a  cycloplegic  in  the 
examination  of  all  candidates  for  admission  to  the  flying  corps. 

The  research  work  done  in  this  laboratory  has  shown  definitely 
that  a  flier's  life  depends,  to  a  great  extent,  upon  his  ability  to  keep 
in  condition,  both  mentally  and  physically.  Loss  of  sleep,  dissipa- 
tion, or  illness  will  so  lower  his  resistance  that  his  eyes  break  more 
readily  under  the  added  strain  of  low-oxygen  tension,  which,  in  actual 
flying,  would  frequently  result  in  death. 

When  every  flier  understands  this  fact  we  will  have  a  more  effi- 
cient flying  corps  and  fewer  accidents. 


274 


AIE  SERVICE  MEDICAL. 


145 


AIK  SERVICE   MEDICAL.  275 

OPHTHAIiMOLOOICAIi   EXAMINATION    OF   THE   FLIEK    DURING    LOW-OXYGEN 

TENSION  EXPERIMENT. 

PEELIMINABY. 

Visual  acuity. — A  Snellen  test  card  is  hung  on  a  level  with  the  can- 
didate's eyes,  at  a  distance  of  20  feet.  Uniform  illumination  is  ob- 
tained by  the  use  of  a  75-watt  nitrogen  daylight  lamp,  placed  1  foot 
from  the  card,  at  an  angle  of  45  degrees.         • 

The  left  eye  is  covered  and  the  vision  of  the  right  eye  recorded  in 
feet.  (Ex.  20/20,  or  if  three  letters  are  missed  in  the  20/20  line, 
20/20-3.)  The  right  eye  being  covered,  the  vision  of  the  left  eye  is 
determined  and  recorded  in  the  same  manner.  Place  a  trial  frame 
before  the  eyes  and  cover  the  left  eye,  place  a  high  plus  sphere  before 
the  right  eye  and  add  minus  spheres  until  the  best  line  read  without 
the  use  of  a  Ifense  is  again  distinct.  This  procedure  is  repeated  for  the 
left  eye,  and  the  strongest  convex  lens  which  still  permits  clear  vision 
is  recorded. 

RETINAL    SENSITIVITY. 

A.  Contrast  sensitivity. —  (1)  This  is  the  test  to 'be  used  in  the 
routine  preliminary  examination.  The  test  object  is  made  by  pasting 
a  1-inch  square  of  gray  paper  on  a  2-inch  square  of  lighter  gray  paper 
where  there  are  13  perceptible  differences  between  the  two  squares. 
The  two  squares  are  mounted  on  a  5-inch  square  of  heavy  cardboard 
for  handling.  The  test  object  is  placed  slightly  above  the  level  of 
the  subject's  eyes  at  a  distance  of  20  feet.  A  75-watt,  110-volt  day- 
light lamp  at  a  distance  of  8|  inches  and  at  an  angle  of  45  degrees  is 
used  to  illuminate  the  test  object.  The  Reeve's  wedge  is  made  by 
coating  a  neutrally  dyed  gelatine  in  a  wedge  shape  on  plate  glass  so 
that  the  absorption  of  light  varies  with  the  thickness  of  gelatine  de- 
posit. A  cover  glass  is  cemented  over  the  gelatine  for  protection. 
The  subject  is  told  the  principle  of  the  wedge  and  what  to  look  for 
when  viewing  the  test  object  through  the  wedge.  Before  making 
any  readings  the  subject  should  be  shown  how  to  keep  his  pupil  in  line 
with  the  aperture  in  the  wedge  case.  The  subject,  with  both  eyes 
open,  then  draws  the  wedge  from  its  case  until  the  contrast  just  dis- 
appears and  the  larger  square  appears  uniform.  When  the  pupil  is 
in  line  the  examiner  should  give  the  word  for  the  wedge  to  be  drawn 
out  of  the  holder.  The  rate  of  movement  should  be  so  regulated 
that  the  contrast  disappears  in  not  less  than  five  nor  more  than  eight 
seconds.  Repeat  until  three  readings  have  been  obtained  and  if  these 
results  are  not  too  discordant  their  average  represents  the  threshold 
for  the  subject. 

(2)  A  20/50  Snellen  illiterate  "E"  is  used  instead  of  the  smaller 
square  and  the  subject  should  be  able  to  tell  which  direction  the  "  E  " 
89118—19 19 


276  ATR  SERVICE  MEDICAL. 

points  when  it  is  shifted — as  he  observes  it  through  the  wedge.  This 
test  is  to  .be  used  in  special  cases ;  suspected  malingering,  etc. 

B.  Threshold  sensitivity. — This  procedure  may  be  employed  to 
check  the  contrast  sensitivity  test. 

At  the  regular  distance  of  20  feet,  with  the  Reeves  wedge  before 
the  right  eye,  the  observer  looks  at  a  3-millimeter  aperture  in  the 
iris  diaphragm  on  the  De  Zeng  stand.  A  36-watt  110-volt  Mazda 
lamp  with  a  frosted  globe  is  used  as  the  source  of  illumination,  the 
candidate  looking  through  the  aperture  in  the  wedge  with  the  right 
eye.  The  wedge  is  drawn  out  until  the  light  just  becomes  invisible, 
the  rate  of  movement  to  be  the  same  as  in  the  determination  of 
contrast  sensitivity.  The  reading  of  the  scale  on  the  wedge  repre- 
sents the  threshold  for  the  adaptation  to  the  brightness  of  the  room. 
(The  absolute  threshold  would  be  represented  by  a  similar  procedure 
when  the  eyes  were  completely  adapted  to  a  total  dancness.)  At 
least  three  readings  should  be  taken  for  this  threshold  and,  if  the 
results  are  too  discordant,  the  examiner  should  repeat  directions  and 
closely  supervise  the  procedure.  When  giving  directions,  the  ex- 
aminer is  getting  the  aperture  in  the  wedge  apparatus  centrally 
aligned  with  the  pupil.  This  threshold  value  represents  the  least 
that  can  be  seen  for  the  particular  adaptation  of  the  retina.  (The 
examiner  should  always  bear  in  mind  that  the  threshold  value  differs 
greatly  for  different  brightness  adaptations  and  different  states  of 
adaptation  to  the  same  brightness.)  The  average  reading  for  the 
wedge  should  be  determined  for  special  conditions  found  at  each 
laboratory.  If  the  eye  is  to  be  adapted  in  an  absolutely  dark  room, 
for  practical  purposes,  the  adaptation  would  be  complete  in  20 
minutes.  If  the  candidate  is  to  be  adapted  for  a  light  room  of 
known  brightness,  for  instance,  a  75-watt  nitrogen  daylight  lamp  in 
a  dark  room,  15  by  10  by  8  feet,  5  minutes'  adaptation  would  be 
sufficient. 

MUSCLE   BALANCE — THE   EOUTINE. 

The  subject's  eyes  should  be  on  a  level  with  and  directly  facing  a 
1-centimeter  black  dot  on  a  white  card  or  the  1  centimeter  opening  in 
the  iris  diaphragm  on  the  De  Zeng  stand,  20  or  25  feet  distant.  It 
is  most  important  to  see  that  the  candidate's  head  is  held  in  the 
vertical  plane  if  errors  in  determining  the  amount  of  hyperphoria 
are  to  be  avoided.  If  a  phorometer  or  Maddox  rod  is  used,  it  is 
well  to  check  the  findings  with  the  screen  and  parallax  test. 

MADDOX  EOD  TEST. 

A  trial  frame  with  a  red  multiple  Maddox  rod,  properly  centered 
before  the  right  eye,  should  be  carefully  adjusted  so  that  there  is  no 
sagging  from  the  horizontal  plane.  The  eyes  are  fixed  on  the  light 
source  and  the  left  eye  is  covered  to  make  sure  that  the  single  bar 


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147 


AIR  SERVICE  MEDICAL.  277 

of  light  is  accurately  observed,  running  horizontally,  when  the  rod 
is  vertical,  and  vertically  when  the  rods  are  horizontal.  The  left  eye 
is  uncovered  and  the  candidate  states  the  exact  position  of  the  red 
line  in  relation  to  the  light.  If  the  red  line,  Avhen  vertical  and  hori- 
zontal, runs  directly  through  the  light  orthophoria  obtains  for  dis- 
tance. If  the  vertical  red  line  is  to  the  left  of  the  lights  (crossed 
diplopia)  there  is  exophoria.  If  the  line  is  to  the  right  of  the  lights 
(homonymous  diplopia)  there  is  esophoria.  The  prism,  placed  base 
in  before  the  left  eye  in  exophoria  and  base  out  in  esophoria,  which 
causes  the  line  to  run  through  the  lights  is  the  measure  of  the  hori- 
zontal imbalance.  If  the  horizontal  line  is  above  the  light  there  is 
left  hyperphoria ;  if  below  the  light,  right  hyperphoria ;  and  the 
prism,  base  up  or  down,  which  causes  the  line  to  run  through  the 
light,  is  the  measure  of  the  vertical  imbalance.  To  remember  that 
high  eye  means  low  image;  and,  when  the  eyes  are  uncrossed,  the 
diplopia  is  crossed,  may  help  one  in  the  study  of  the  heterophorias. 

Some  candidates  may  not  understand  the  rod  test,  or  they  may  have 
been  coached  to  saj'^  that  the  rod  runs  through  the  light,  so  always 
check  the  findings  with  the  screen  and  parallax  test  or  use  the  rod  in 
combination  with  a  prism  which  would  produce  a  known  deviation 
of  the  line. 

SCREEN  AND  PARALLAX  TEST. 

t 

The  candidate  is  seated  6  meters  from  a  1-centimeter  light  on  a 
black  field  or  a  1-centimeter  black  dot  on  a  white  field,  which  he 
fixes  intently.  Shift  a  card  quicklj''  from  eye  to  eye  and  note  any 
movement  of  the  eye  as  it  is  uncovered  and  ask  the  candidate  to 
describe  any  movement  of  the  eye  or  the  light.  Orthophoria  obtains 
if  there  is  no  apparent  movement  of  the  eye  or  the  light.  Movement 
of  the  test  object  or  eye  with  the  card  signifies  exophoria;  against 
the  card,  esophoria;  and  vertical  movement,  hyperphoria.  Prisms 
are  placed  with  the  base  in  for  exophoria,  out  in  esophoria,  up  before 
the  right  eye  in  left  hyperphoria,  and  down  in  right  hyperphoria, 
until  the  test  object  and  the  eye  just  begin  to  move  in  the  opposite 
direction.  The  weakest  prism  which  causes  reversal  of  movement, 
minus  2  prism  degrees,  is  the  measure  of  the  heterophoria.  If  there 
is  less  than  5  degrees  of  heterophoria,  only  1  prism  degree  is  sub- 
tracted. 

N.  B. — In  hyperphoria  first  correct  the  horizontal  imbalance  and 
then  superimpose  the  square  prisms  to  determine  the  amount  of  verti- 
cal imbalance.  The  prism  which  just  stops  the  movement  gives  the 
measure  of  the  hyperphoria. 

If  muscle  imbalance  of  more  than  1  degree  is  found  in  either  plane, 
the  Maddox  rod.  and  screen  and  parallax  tests  should  be  made  at  14 
inches,  using  a  2-millimeter  black  dot  on  a  white  card  or  the  light  of 


278  AIB   SERVICE   MEDICAL. 

the  Hare-Marple  ophthalmoscope  as  the  test  object.  The  converging, 
diverging,  and  siirsumverging  power  should  also  be  taken  and  re- 
corded on  back  of  the  5  by  8  history  card. 

Example. — In  testing  the  power  of  convergence  the  subject  fixes  the 
1 -centimeter  black  dot  at  20  feet,  and  prisms  of  increasing  strength 
are  placed,  base  out,  before  either  eye  until  the  diplopia  produced 
can  not  be  overcome.  The  strongest  prism  through  which  binocular 
single  vision  is  obtained  is  the  measure  of  the  converging  power. 
Practice  is  important,  especially  in  determining  the  power  of  con- 
vergence. It  is  well  to  begin  with  a  very  weak  prism  and  gradually 
increase  the  strength,  permitting  the  subject  to  close  his  eyes  and  then 
open  them  quickly  when  he  has  difficulty  in  fusing  the  test  object. 
In  testing  the  diverging  powder,  prisms  are  placed  base  in  and  gradu- 
ally increased  in  strength.  To  make  certain  that  the  candidate  is 
really  fusing,  the  prism  may  be  rotated  a  little,  producing  a  vertical 
diplopia,  and  then  brought  back  to  the  horizontal,  or  the  eyes  may 
be  screened  alternately  and  any  movement  of  the  unscreened  eye 
noted.  The  right  sursumverging  power  is  tested  with  the  prism  base 
down.  Before  making  a  definite  statement  as  to  the  strength  of  the 
muscles  it  is  well  to  have  the  candidate  return  several  times,  for,  as 
has  been  said,  practice  and  knack  play  a  great  part  in  this  examina- 
tion. Always  test  the  divergence  first,  then  the  sursumvergence,  and 
finally  the  convergence. 

MUSCLES. 

If  there  is  a  marked  imbalance  of  the  ocular  muscles,  it  will  be  well 
to  use  a  black  wall  as  a  tangent  screen  and  make  a  record  of  the 
diplopia  in  the  various  fields  as  obtained  by  the  use  of  the  ruby  glass 
and  light  at  a  distance  of  30  inches  from  the  wall.  This  should  be 
lecorded  on  the  tangent  screen  charts  which  have  been  provided  and 
filed  with  the  5  by  8  history  card. 

ACCOMMODATION    (NEAR  POINT). 

The  near  point  accommodation  is  measured  by  means  of  the  Prince 
rule,  using  the  type  Jaeger  No.  1,  or  the  Duane  disk,  as  the  test  object. 
The  Prince  rule  ha^  been  gouged  out  at  one  end  to  permit  its  use  in 
the  midline,  as  in  this  way  it  can  be  placed  over  the  nose,  in  contact 
with  an  ink  mark  which  is  12  millimeters  in  front  of  the  cornea. 
This  point  is  measured  by  placing  a  millimeter  rule  alongside  the 
forehead  and,  with  the  gaze  fixed  straight  ahead,  12  millimeters  are 
measured  off.  The  point  thus  determined  is  marked  on  the  nose. 
The  test  object  is  brought  slowly  toward  the  eye  until  the  first  sign 
of  blurring  is  noted.  This  procedure  is  repeated  several  times,  in- 
structing the  candidate  to  exert  all  his  power  so  that  the  test  object 


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AIR   SERVICE   MEDICAL.  279 

jTiay  be  brought  as  close  to  the  eye  as  possible,  for  we  know  that  the 
first  contraction  of  a  muscle  is  seldom  its  strongest.  The  reading  at 
which  the  test  object  was  brought  closest  to  the  eye  is  recorded  in  milli- 
meters. It  is  well  to  have  a  good  light  from  a  75-watt  nitrogen  day- 
light lamp  shining  directly  on  the  type,  and  the  test  is  more  accurate 
if  the  test  type  is  held  slightly  below  the  horizontal  plane. 

PUPILLARY    DIAMETER. 

With  the  cajididate  seated  in  the  chair  in  which  he  is  to  be  tested, 
and  with  the  same  light  that  will  be  used  later  on,  he  is  asked  to  fix 
a  distant  object.  A  millimeter  rule  is  inverted  above  the  pupil  with 
a  plus  2.75  sph.  superimposed,  and  the  reading  is  made  while  looking 
through  the  lens.  If  greatei-  accuracy  is  desired,  a  pupillometer 
should  be  used. 

COLOR   VISION. 

For  this  purpose  Jenning's  color  test  is  used.  The  method  of 
making  the  test :  The  cover  of  the  green  side  of  the  box  is  removed, 
the  color  board  is  lifted  out,  a  record  sheet  inserted,  and  the  color 
board  replaced.  In  replacing  the  color  board  CAKE  MUST  BE 
TAKEN  TO  SEE  THAT  ITS  TOP.  MARKED  ON  THE  BACK 
^•NO.  1  GREEN,"  CORRESPONDS  TO  THE  TOP  OF  THE 
RECORD  SHEET.  The  box  is  now  turned  around  several  times 
until  all  sense  of  direction  is  lost.  The  green  test  skein,  fastened 
to  the  inside  of  the  box  lid,  is  placed  at  a  distance  of  2  feet  and 
the  candidate  is  given  the  stylus  and  requested  to  look  along  each 
row  of  colored  patches  and  when  he  sees  the  test  color,  or  one  of 
its  lighter  or  darker  shades,  he  is  to  place  the  point  of  the  stylus  in 
the  opening  and  punch  a  hole  in  the  paper  beneath.  Have  him 
understand  that  he  is  not  expected  to  find  an  exact  match  for  the 
test  skein  but  that  he  is  to  indicate  all  the  color  patches  that  appear 
to  him  to  be  same  general  color  as  the  test  skein,  both  those  that  are 
lighter  and  those  that  are  darker  in  shade.  Having  completed  Test 
No.  1,  the  record  sheet  is  removed,  the  cover  is  replaced,  and  the  box 
turned  over,  exposing  Test  No.  2,  the  ROSE.  The  same  record  sheet 
is  placed  under  the  rose  color  board,  CARE  BEING  TAKEN  TO 
HAVE  THE  TOP  OF  THE  RECORD  SHEET  AND  THE  TOP 
OF  THE  COLOR  BOARD,  MARKED  O^^  THE  BACK  "NO. 
2  ROSE,"  correspond.  The  rose  test  skein  is  now  displayed  and 
the  test  proceeds  as  before.  If  the  candidate  seems  to  have  been 
uncertain  in  the  selection  of  colors  or  you  suspect  that  he  may  have 
been  coached  in  the  test,  turn  the  card  with  the  colored  wools  and 
the  blank  on  the  reverse  side  and  have  another  reading  made.    An- 


280  AIB  SERVICE   MEDICAL. 

other  way  to  confuse  the  subject  is  to  cut  a  circle  in  a  piece  of  paper 
and  place  it  over  the  peripheral  skeins. 

BEACTION    OF   THE    IBIS    TO    LIGHT    AND    ACCOMMODATION. 

The  reaction  of  the  iris  to  direct  and  indirect  light  and  accom- 
modation is  noted  and  recorded  as  plus  (meaning  reacts)  1,  2,  and  3, 
being  increased  reaction,  minus  1,  2,  and  3  meaning  degrees  of  slug- 
gish reaction,  and  0  no  reaction.  The  reaction  to  accommodation  is 
determined  by  requiring  the  candidate  to  look  in  the  distance  and 
then  fix  on  a  2-millimeter  black  dot  on  a  white  card  held  10  centi- 
meters in  front  of  the  eye.  The  reaction  to  light  is  best  taken  in  a 
dark  room,  requiring  the  candidate  to  look  into  the  distance  and 
directing  light  from  the  Hare-Marple  ophthalmoscopic  mirror  through 
the  pupil  and  noting  the  reaction  in  both  eyes.  It  may  be  taken 
more  roughly,  with  the  candidate  facing  a  window  and  fixing  a  dis- 
tant object,  both  eyes  being  covered;  the  covers  are  removed  alter- 
nately and  the  reaction  to  direct  and  indirect  light  noted. 

NEAB  POINT  OF  CONVEEGENCE. 

The  Prince  rule  and  a  2-millimeter  black  dot  as  a  test  object  are 
used.  The  end  of  the  rule  rests  across  the  bridge  of  the  nose  at  a 
point  12  millimeters  in  front  of  the  cornea.  The  test  object  is 
brought  slowly  toward  the  eyes  slightly  below  the  horizontal  plane 
until  there  is  a  doubling  of  the  dot  or  one  or  both  of  the  candidate's 
eyes  ceases  to  fix.  The  test  is  repeated  several  times,  instructing  the 
candidate  to  exert  his  maximum  eflfort,  and  the  reading  which  was 
closest  to  the  eye  is  recorded. 

STEBEOSCOPIC    VISION. 

An  ordinary  stereoscope  and  the  A,  B,  and  C  cards  are  furnished. 
The  stereoscope  should  be  held  away  from  the  candidate's  eyes  and 
gradually  brought  up  to  them,  instructing  him  that  he  is  to  look  at 
the  pictures  just  as  he  would  look  at  objects  in  a  show  case  in  a  store 
window.  He  is  then  asked  to  move  the  card  backward  and  forward 
until  the  point  is  reached  at  which  the  pictures  are  most  distinct,  and 
his  eyes  are  most  comfortable.  He  is  then  asked  to  name  the  objects 
by  number  as  he  sees  them,  from  before  backward.  The  usual  order 
with  the  A  card  is  9-1-7,  3-2-4,  5-6-8,  and  10.  Confusion  of  4  and  5, 
9  and  1,  and  8  and  10  is  permissible.  To  further  test  the  candidate 
on  the  same  card,  he  may  be  asked  to  name  the  smaller  objects  on 
No.  9,  from  before  backwards,  they  are  cross,  balloon,  and  flag.  On 
No.  8,  balloon,  cross,  rod,  and  pennant.  No.  10,  pennant,  balloon, 
and  cross.  The  usual  order  for  the  B  card  is  7-5-9,  3-4-2,  1-10-8, 
and  6;  for  the  C  card,  10-9-2,  7-8-6,  4-3-1,  and  5. 


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AIE  SEEVIOE  MEDICAL.  281 

OPHTHALMOSCOPIC   EXAMINATION. 

The  direct  and  indirect  methods  should  be  used,  noting  any 
changes  in  the  lens,  media,  or  fundus. 

Preliminary  Report  of  the  Research  Work  of  the  Ophthalmo- 
LOGiCAL  Department,  Medical  Research  Laboratory,  July  17, 
1918. 

Although  the  number  of  men  examined  has  been  few  and  the 
research  work  carried  out  under  adverse  conditions,  an  outline  of 
the  results  so  far  accomplished  may  prove  of  some  value  in  helping 
us  care  for  the  flier  in  a  more  scientific  manner. 

The  most  important  problem  is  the  one  of  visual  acuity,  and  it  is 
absolutely  essential  that  the  pilot  or  observer  have  as  nearly  perfect 
vision  as  nature  permits  under  noraial  conditions,  and  furthermore 
that  the  visual  acuity  will  not  show  a  marked  deterioration  due  to 
the  lack  of  oxygen. 

Visual  acuity  has  been  studied  using  Ives'  test  object  and  John- 
son's visual  acuity  test  apparatus  and  also  with  the  ordinary  Snellen 
test  type.  The  Ives'  visual  acuity  test  object  has  been  found  to  be 
of  the  greatest  value  for  taking  the  visual  acuity  on  the  rebreathing 
apparatus,  due  to  the  fact  that  the  subject  could  raise  his  hand  when 
he  first  perceived  the  lines.  In  the  low-pressure  chamber  it  has  also 
proven  of  value,  for  the  first  surface  mirror  could  be  used  to  increase 
the  reading  distance. 

Forty-four  subjects  were  examined  on  the  rebreathing  apparatus 
and  in  the  low-pressure  chamber.  They  were  classified  as  normal 
and  subnormal;  i.  e.,  those  who  could  pass  the  examination  for  the 
Department  of  Military  Aeronautics  and  those  who  would  be  ocu- 
larly disqualified.  The  13  subnormal  subjects  were  so  classified  be- 
cause of  defective  vision  arising  from  errors  of  refraction. 


Vision  improved. 
Vision  decreased. 
No  change 


Normal. 


3  (10  per  cent).. 
8  (26  per  cent).. 
20  (64  per  cent). 


Subnormal. 


5  (38.5  per  cent). 
8  (61.5  pe/  cent) . 


One  of  the  French  observers  claimed  that  the  visual  acuity  in- 
creases at  an  altitude  of  2,000  meters  and  that  this  was  probably  due 
to  congestion  of  the  head  and  in  particular  of  the  choroid  and  retina. 
Normal  visual  acuity  readings  were  taken,  using  the  Johnson  appa- 
ratus, then  a  three-minim  pearl  of  amyl  nitrite  was  inhaled  to  pro- 
duce congestion.  Twelve  men  were  examined  and  there  was  im- 
pairment of  vision  during  the  period  of  maximum  nitrite  effect  in  all 
except  one,  a  myope.  During  the  first  stage  of  the  action  of  the  drug 
there  was  a  slight  increase  in  visual  acuity  in  most  instances. 


282  AIR   SERVICE   MEDICAJL. 

The  effect  of  tobacco  upon  the  visual  acuity  has  also  been  studied. 
Smoking  one  strong  cigar  or  inhaling  one  or  two  cigarettes,  controls 
were  made  in  most  instances.  Twelve  or  75  per  cent  showed  falling 
off  in  visual  acuity  over  the  control,  6  per  cent  showed  a  rise,  and 
three,  or  19  per  cent,  showed  no  change.  This  subject  will  be  taken 
up  m  full  under  the  effects  of  tobacco  on  the  eye. 

REACTION  TIME. 

The  French  and  Italians  have  laid  great  stress  upon  the  determina- 
tion of  the  reaction  time,  and  it  is  undoubtedly  important  that  the 
pilot  or  observer  act  and  think  a  little  more  rapidly  than  his  adver- 
sary, if  he  is  to  have  the  advantage.  All  the  men  who  have  done  the 
most  work  in  reaction  time  in  this  country  believe  that  some  form  of 
complex  reaction  time  will  prove  of  value,  but  they  are  skeptical  as  to 
the  results  obtained  with  the  simple  reaction  time  tests  employed  by 
the  French  and  Italians.  With  this  in  mind  the visual  dis- 
crimination reaction  time  experiment  with  four  possible  correct  reac- 
tions and  five  possible  stimuli  has  been  chosen.  The  subject  presses 
the  telegraphic  key  the  moment  the  stimulus  appears  upon  the  ground- 
glass    plate.     The  chronoscope    starts    recording    time    the 

moment  the  light  appears  on  the  ground  glass  and  is  stopped  by  the 
subject's  reaction.  The  chronoscope  records  time  in  0.12  of  a  second 
and  the  average  discrimination  reaction  of  a  normal  subject  is  ap- 
proximately one-half  second,  and  for  simple  reaction  time  one-fifth 
of  a  second. 

JUDGMENT  or  DISTANCE  AND  STEREOSCOPIC  VISION. 

There  are  many  factors  involved  in  the  judgment  of  distance,  but 
undoubtedly  stereopsis  is  of  importance  in  the  accurate  performance 
of  this  complex  act  and  therefore  it  has  been  considered  important 
that  the  stereoscopic  vision  be  tested  under  conditions  of  low-oxygen 
tension. 

The  stereoscopic  vision  was  tested  on  the  rebreather  and  in  the 
low-pressure  chamber  by  use  of  the  ordinary  stereoscope  containing 
7-degree  prisms,  base  out,  with  a  plus  5.50  sphere  superimposed. 
The  ability  to  maintain  perfect  stereopsis  at  high  altitudes  was 
noted. 

Nineteen  normal  subjects  were*examined  on  the  rebreather  with  a 
loss  of  stereopsis  in  only  three  of  them,  or  15.7  per  cent.  Readings 
were  taken  at  six-minute  intervals  throughout  the  run.  Of  seven 
men  ocularly  disqualified  stereopsis  was  lost  in  only  one.  In  no 
case  was  a  change  noted  below  20,000  feet. 

Seven  "normals"  and  nine  "subnormals"  were  examined  in  the 
low-pressure  chamber.     Here  readings  were  taken  at  10,000,  15,000, 


AIE   SEBVICE   MEDICAL.  283 

and  20,000  feet.  All  seven  normals  remained  unchanged  and  only 
one  subnormal  showed  any  confusion  in  stereopsis.  This  change 
was  noted  at  15,000  feet,  but  normal  stereopsis  was  promptly  re- 
stored bj-  the  administration  of  oxygen. 

COLOR  VISION. 

Color  vision  is  considered  important  for  the  flier  by  most  of  the 
allied  nations,  and  certainly  it  plays  an  important  role  in  judging 
the  color  of  fields  and  swamps  in  landing.  To  accurately  determine 
the  color  of  roofs,  chimneys,  lights,  etc.,  particularly  colored  lights 
at  night,  good  color  vision  is  surely  necessary.  We  have  endeavored 
to  determine  the  effect  of  low-oxygen  tension  upon  color  vision. 
Stillings  plates  were  used  in  these  tests.  Fii'^e  subjects  were  carried 
to  20,000  feet  or  over  in  the  low-pressure  chamber  and  five  above 
20,000  feet  on  the  rebreathing  apparatus.  There  was  no  change  in 
color  vision  during  these  tests. 

FIELD  OF  BINOCULAR  SINGLE  VISION  AND  FIELD  OF  BINOCULAR  FIXATION. 

The  field  of  binocular  single  vision  has  been  tested  by  means  of 
a  tangent  screen.  The  field  of  binocular  fixation  has  been  tested 
by  the  use  of  the  modified  Schweiger  perimeter  and  small  dots  on  a 
white  card.  One  hundred  and  twenty-two  men  with  normal  eyes 
were  examined  and  16  who  were  ocularly  subnormal.  Seven  and 
thirty-seven  one-hundredths  per  cent  of  the  normals  showed  contrac- 
tion of  the  field  of  binocular  fixation.  Fifty  per  cent  of  the  subnor- 
mals showed  this  contraction.  Contraction  of  the  field  was  more 
marked  above. 

MUSCLE  BALANCE  AND  MUSCLE  STRENGTH. 

It  is  important  for  the  flier  that  his  muscle  balance  be  ^s  nearly 
normal  as  possible,  for  small  defects  are  accentuated  by  the  strain  of 
fl^dng  and  lack  of  oxygen,  resulting  in  a  marked  contraction  of  the 
field  of  binocular  single  vision,  and  sometimes  diplopia  is  produced, 
even  at  low  altitudes.  Eesearch  work  has  demonstrated  that  exo- 
phoria  and  hyperphoria  are  more  objectionable  than  esophoria. 

To  determine  the  effect  of  lack  of  oxygen  upon  the  ocular  muscles 
35  men,  acceptable  for  the  Air  Service,  have  been  examined  on 
the  rebreathing  apparatus  and  the  findings  checked  by  repeating 
the  test  in  the  low-pressure  chamber.  The  muscle  duction  was 
taken  at  sea  level,  5,000,  10,000,  15,000,  and  20,000  feet,  and  at 
this  point  oxygen  was  given  in  the  low-pressure  chamber  for  five 
minutes,  and  on  the  rebreathing  apparatus  the  mouthpiece  was  taken 
out,  allowing  the  subject  to  breathe  normally.     Oxygen  or  breathing 


284 


Am  SERVICE  MEDICAL. 


atmospheric  air  caused  a  return  of  the  muscle  strength  to  normal  in 
from  three  to  five  minutes.  The  general  averages  of  the  strength  of 
the  muscles  at  sea  level  is  as  follows : 


Superduction. 
2.8" 

Abduction. 
6.2" 

Adduction. 
16.8° 

Loss  of  strength  during  the  rebreathing  test: 

15  000  feet  or  11.8  ner  cent  oxveen 

•■      P.  ct. 
1. 1      (39) 
1.9      (70) 

1.05  (37) 
1.7      (64) 

•      P.  ct. 
1. 5      (24) 
L83    (29) 

1.35  (21) 
1.8      (29) 

P.ct. 
1.8    (9.5) 

20  000  feet  or  9  7  ner  cent  oxveen 

2.94     (17) 

Loss  of  strength  during  low  pressure  chamber  test: 

15  000  feet  or  11.8  per  cent  oxveen 

L75    (10) 

20.000  feet  or  9.7  ner  cent  oxveen 

2. 8      (16) 

In  all  the  subnormal  subjects  examined,  particularly  those  with 
convergence  insufficiency  alone  or  combined  with  divergence  excess, 
there  was  a  marked  loss  in  the  power  of  adduction,  and  diplopia 
often  occurred  between  10,000  and  15,000  feet.  Men  with  over  one 
degree  of  hyperphoria,  particularly  when  combined  with  exophoria, 
showed  a  rapid  reduction  in  muscle  strength,  often  resulting  in 
diplopia.  Subjects  in  the  subnormal  group  should  be  cared  for  by 
muscle  exercises  and  operations  where  it  is  found  necessary. 

FIELD  OF  VISION. 

It  is  of  the  utmost  importance  that  the  aviator  have  the  broadest 
possible  field  of  vision,  for  we  know  that  the  visual  field  is  contracted 
slightly,  due  to  the  lack  of  oxygen,  and  that  marked  constriction  of 
the  field  is  produced  by  poorly  constructed  goggles  as  well  as  by  blind 
angles  in  aeroplane  construction.  The  fields  for  form  and  color  have 
been  taken  in  the  low-pressure  chamber  at  5,000,  10,000,  15,000,  and 
20,000  feet,  and  when  contraction  is  noted  at  20,000  feet  oxygen  is 
administered.  To  make  sure  that  the  changes  are  not  due  to  fatigue, 
controls  have  been  taken  at  sea  level,  corresponding  in  time  of  day 
and  in  time  interval  to  those  taken  in  the  low-pressure  chamber.  At 
5,000  and  10,000  feet  there  is  usually  a  slight  enlargement  of  the 
fields  for  form  and  color,  at  15,000  feet  a  slight  contraction,  and  at 
20,000  feet  a  marked  contraction.  Twenty  men  have  been  examined, 
and  at  20,000  feet  the  fields  for  form  have  shown  a  contraction  of  14 
per  cent  of  their  original  size  below,  3.5  per  cent  in  the  temporal 
field,  4  per  cent  above,  and  6  per  cent  nasally.  The  green,  4.5  per 
cent  in  the  lower,  5  per  cent  in  the  temporal,  5  per  cent  above,  and  25 
per  cent  in  the  nasal  field.  Five  minutes  after  returning  to  sea  level 
fields  are  normal  in  size.  Giving  oxygen  at  20,000  feet  for  four  or 
five  minutes  caused  a  return  of  the  fields  to  normal.  Several  fields 
have  been  taken  on  the  rebreathing  apparatus,  and  the  results  are 
fairly  comparable  with  those  found  in  the  low-pressure  chamber. 


AIE   SEEVICE   MEDICAL. 


285 


PERCEPTION   OF   MOTION   BY   THE  RETINA. 

It  is  important  that  the  aviator  note  the  approach  of  an  enemy 
plane  before  the  enemy  sees  him,  and  therefore  the  keen  sense  of 
perception  of  motion  by  the  retina  is  a  valuable  asset  to  the  flier.  It 
has  been  our  endeavor  to  provide  some  method  of  taking  and  record- 
ing these  fields  in  the  hope  that  something^  of  practical  value  might 
be  found. 

These  fields  were  taken  in  a  dark  room  with  no  illumination  other 
than  that  of  the  test  object,  for  Avhich  purposes  a  May  ophthalmoscope 
battery  handle  with  the  cap  removed  was  used. 

The  subject  was  seated  at  a  distance  of  15  inches  from  the  center 
of  the  screen.  The  test  object  was  held  on  the  opposite  side 
of  the  screen  from  the  object  and  gradually  moved  until  it  came  into 
the  field  of  vision.  In  this  manner  the  place  at  which  the  motion  of 
the  light  could  be  first  seen  was  noted,  and  then  at  what  point  the 
correct  perception  of  direction  of  motion  could  be  ascertained.  Lastly, 
the  field  of  form  was  taken,  i.  e.,  the  first  point  at  which  the  stationary 
light  could  be  recognized. 

The  relative  sizes  of  these  three  fields  can  be  seen  by  the  average 
figures  of  10  cases : 


Field  of 
form. 


Up 

Down 

Right 

Left 

Up  and  ripjht .  -  - 

Up  and  left 

DowTi  and  right 
Down  and  left.. 


291 

m 

40 

421 

35 

36 

43 

43 


The  field  of  motion  is  approximately  3  degrees  larger  than  the 
field  of  direction  of  motion,  which,  in  turn,  is  about  1^  degrees 
larger  than  that  of  form.  It  is  evident,  then,  that  a  moving  object 
can  be  seen  4r|  degrees  sooner  than  a  stationary  one.  That  is,  the 
field  of  motion  is  4J  degrees  larger  in  every  direction  than  that  of 
form.  This  relationship  is  apparently  a  constant  one,  independent 
of  the  size  of  the  field.  In  other  words,  if  motion  is  perceived  at  a 
certain  point,  you  expect  to  find  the  perception  of  form  4^  degi'ees 
farther  in  toward  the  center.  In  a  like  manner  the  field  of  percep- 
tion of  direction  of  motion  bears  a  rather  constant  relationship  to 
that  of  motion  and  of  form. 


INTRAOCULAR  TENSION. 


Intraocular  tension  has  been  studied  in  the  low-pressure  chamber. 
Fourteen  men  have  been  examined  in  the  low-pressure  chamber. 
No  correlation  has  been  found,  either  between  intraocular  tension 


286  Are  SERVICE  medical. 

and  the  blood  pressure  or  lowered  oxygen  tension  and  various  cardio- 
vascular changes,  for  the  intraocular  tension  has  sometimes  gone  up 
as  the  barometric  pressure  was  lowered  and  sometimes  it  has  gone 
down  with  the  lowering  of  barometric  pressure.  This  also  holds 
true  for  the  blood  pressure.  However,  before  definite  conclusions 
should  be  made  more  work  should  be  done. 

ACCOMMODATION. 

The  flier  must  continually  observe  the  instruments  on  the  inside 
of  the  fuselage,  particularly  at  night,  and  therefore  it  is  important 
that  the  accommodation  should  not  fall  off  too  rapidly,  due  to  lack 
of  oxygen.  The  rule  of  accommodation  in  visual  acuity  and  in 
judgment  of  distance  is  also  important. 

The  near  point  of  acconmfiodation  has  been  taken  every  two  min- 
utes in  the  low-pressure  chamber  and  on  the  rebreathing  apparatus, 
using  a  Prince  rule  with  Jaeger  test  type  or  the  Duane  disk  as  a 
test  object.  Normal  runs  have  been  made  without  the  low  oxygen 
tension  effect  for  the  purpose  of  comparison.  One  hundred  and 
forty-eight  men.  acceptable  for  the  Aviation  Service  as  fliers,  were 
examined  on  the  rebreathing  apparatus:  44.6  per  cent  showed  a 
receding  of  the  near  point.  18  per  cent  showed  improvement,  fluctu- 
ating changes  in  accommodation  were  noticed  in  14.4  per  cent,  and 
no  change  in  23  per  cent.  Eleven  subnormal  cases  were  examined, 
and  63.7  per  cent  manifested  a  decrease  in  accommodative  power, 
18.3  per  cent  an  apparent  increase,  9  per  cent  showed  no  change,  and 
9  per  cent  variable  reactions.  The  low  pressure  chamber  findings 
were  practically  the  same  as  those  with  the  rebreather.  Of  IT 
normal  men  examined,  47  per  cent  showed  decrease  in  accom> 
modative  power,  11.7  per  cent  increase,  23  per  cent  fluctuation,  and 
7.8  per  cent  no  change.  Three  subnormal  subjects  were  examined  in 
the  low-pressure  chamber;  two  showed  a  decrease  in  accommodative 
power  and  the  other  gave  a  varying  reaction.  When  the  subject  is 
brought  to  sea  level  the  accommodation  comes  back  rapidly  in  some 
and  slowly  in  others.  The  inhalation  of  oxygen  invariably  causes  a 
return  to  normal,  even  though  the  subject  may  be  kept  at  20.000  feet 
in  the  low-pressure  chamber. 

That  these  changes  do  not  follow  the  cardio-vascular  reactions  is 
shown  by  the  fact  that  57  men,  exhibiting  acceleration  of  pulse  rate 
and  maintenance  of  pulse  pressure,  showed  in  42.1  per  cent  decrease 
in  the  powder  of  accommodation,  15.8  per  cent  increase  in  power  of 
accommodation,  15.8  per  cent  fluctuation  in  accommodation,  and  26.3 
per  cent  no  change  in  accommodation.  Our  researches  would  lead  us 
to  believe  that  hyperopes  and  subjects  with  a  marked  amount  of 
hyperopic  astigmatism  show  the  most  marked  changes  in  accommo- 
dation. 


AIB   SEKVICE    MEDICAL.  287 

Fatigue  of  acconiiuodation  has  been  studied  with  an  ophthahnic 
ergograph.  Normal  three-minute  runs  were  made  without  the  low 
oxygen  tension  effect  as  controls,  then  three-minute  runs  with  same 
time  interval  were  made  in  the  low-pressure  chamber  and  on  the 
rebreathing  apparatus.  The  findings  on  the  rebreathing  apparatus 
and  in  the  k>w-pressure  chamber  showed,  at  15,000  feet,  a  more  rapid 
onset  of  fatigue  than  was  evidenced  by  the  controls,  and  at  20,000 
feet  the  fatigue  was  marked.  The  administration  of  artificial  oxygen 
rapidly  restored  the  normal  tone  of  the  ciliary  muscle. 

CONXTIRGENCE. 

If  the  near  point  of  convergence  falls  off  markedly  during  flying, 
(he  aviator's  ability  to  make  landings  properly  will  be  impaired,  and, 
therefore,  the  near  point  of  convergence  has  been  taken  during  the 
rebreathing  test  and  low-pressure  chamber  experiment. 

A  U-shaped  piece  was  cut  out  of  the  Prince  rule  to  fit  over  the 
nose  and  a  2-millimeter  black  dot  on  a  white  background  was  used  as 
a  test  object  for  making  this  determination.  Readings  were  taken 
without  low-oxygen  tension  effect,  with  low-oxygen  tension  effect,  and 
the  effect  of  the  administration  of  oxygen  was  determined.  Read- 
ings were  taken  every  two  minutes  and  charted.  One  hundred  and 
forty-seven  men  with  normal  eyes  were  examined  (m  the  rebreathing 
apparatus. 

50.3  per  cent  decrease  in  convergence  power. 
17.6  per  cent  increase  in  convergence  power. 

11.5  per  cent  fluctuation  in  convergence  power. 

20.6  per  cent  no  change  in  convergence  power. 

Of  11  subnormal  men  examined  6  were  disqualified  for  visual  acuity 
and  5  for  muscular  imbalance;  45.7  per  cent  showed  decrease  in  power 
of  convergence.  Increased  converging  power,  fluctuating  changes, 
and  no  change  in  the  near  point  of  convergence  were  each  noted  in 
18.1  per  cent.  Of  16  normal  men  examined  in  the  low-pressure  cham- 
ber 50  per  cent  showed  falling  off  in  power  of  convergence,  none 
showed  increase,  fluctuating  reactions  were  present  in  12,5  per  cent, 
and  37.5  per  cent  remained  unchanged.  In  the  subnormal  group 
the  recession  of  the  near  point  of  convergence  was  very  marked, 
sometimes  resulting  in  diplopia. 

An  attempt  has  been  made  to  show  what  relationship,  if  any, 
exists  between  the  convergence  and  the  cardio-vascular  reactions  to 
low-oxygen  tension. 

Seventy-two  cases  showing  an  increase  in  pulse  rate  and  a  main- 
tenance in  pulse  pressure  gave  these  convergence  changes,  which 


288  AIB   SERVICE  MEDICAL. 

would  seem  to  indicate  that  ocular  changes  can  not  be  predicted  by 
the  cardio-vascular  reaction  and  vice  versa. 

54.2  per  cent  decrease  in  power  of  convergence. 

15.3  per  cent  increase  in  power  of  convergence. 
9.7  per  cent  fluctuation  in  power  of  convergence. 

20.8  per  cent  no  change  in  power  of  convergence. 

The  results  would  indicate  that  the  rebreathing  apparatus  and 
low-pressure  tank  give  almost  identical  findings,  and  in  each  case 
the  determining  factor  seems  to  be  the  lowering  of  oxygen  tension 
as  the  administration  of  oxygen  soon  causes  the  convergence  near 
point  to  return  to  normal,  irrespective  of  the  barometric  pressure. 

Fatigue  of  convergence  has  been  studied  with  Howe's  ophthalmic 
ergograph.  Normal  3-minute  runs  as  controls  were  made  without 
the  low  oxygen  tension  effect,  then  3-minute  runs  with  approximately 
the  same  time  interval  were  made  in  the  low-pressure  chamber  and 
on  the  rebreathing  apparatus.  The  findings  on  the  rebreathing 
apparatus  and  in  the  low-pressure  chamber  showed  a  more  rapid 
onset  of  fatigue  than  occurred  with  the  controls.  At  15,000  feet  and 
at  20,000  feet  the  fatigue  was  marked,  as  was  the  case  with  accom- 
modation. Here  also  the  administration  of  oxygen  caused  a  rapid 
return  of  converging  power. 

RETINAL   SENSITIVITY. 

The  Italians  have  laid  considerable  stress  upon  retinal  sensitivity 

for  those  men  who  must  fly  at  night,  and  Lieut.  has  devised 

a  test  for  the  contrast  sensitivity  of  the  retina  which  has  proven 
most  useful  and  practical. 

It  is  important  that  the  retina  be  normally  sensitive  to  light  im- 
pressions, especially  for  those  men  who  must  fly  at  night,  notably 
bombers  and  fliers  doing  patrol  duty.  A  test  for  the  contrast  sen- 
sitivity of  the  retina  has  proven  most  practical  for  our  work,  and 
only  men  who  have  normal  sensitivity  in  this  respect  will  be  selected 
for  night  flying. 

In  this  laboratory  tests  to  determine  the  threshold  sensitivity  for 
white  and  colored  lights  and  for  contrast  are  conducted  in  the  follow- 
ing manner : 

The wedge  is  made  of  two  pieces  of  glass  at  a  known  angle, 

between  which  is  run  a  solution  of  gelatine  and  neutral  dye.  The 
wedge  is  calibrated  in  millimeters,  which  is  translatable  into  per 
cent  of  light  transmitted. 

To  test  the  threshold  sensitivity  to  light  the  subject  is  placed  20 
feet  from  a  spot  of  light  3  millimeters  in  diameter.  Holding  the 
wedge  before  the  right  eye,  he  slowly  draws  the  slide  from  its  cover. 


ATR  SERVICE   MEDICAL.  289 

and  as  the  light  just  disappears  a  reading  ia  taken.  This  reading 
is  in  millimeters  and  is  then  translated  to  per  cent  transmission. 

The  threshold  for  color  is  taken  the  same  as  the  above,  using  red 
and  green  light,  which  are  practically  monochromatic. 

The  test  of  contrast  sensitivity  is  made  vpith  a wedge  and 

contrast  square.     The  contrast  square  is  made  by  placing  a 

square  of  dark  gray  paper  upon  a  larger  square  of  lighter  gray,  there 
being  13  perceptible  differences  between  the  two  shades.  An  illit- 
erate "  E  "  with  the  same  perceptible  differences  is  used  as  a  check  of 
the  findings.  This  is  lighted  by  a  75-watt  nitrogen  daylight  lamp  at 
a  given  angle  and  distance  from  the  test  object  and  the  subject  is 
placed  20  feet  in  front  of  the  object.  The  reading  on  the  wedge  is 
taken  just  as  the  contrast  between  the  squares  disappears.  The  aver- 
age readings  taken  with  the  contrast  sensitivity  square  give  34  milli- 
meters and  the  illiterate  "  E  "  32  millimeters.  To  date,  the  normal 
for  the  light  threshold  of  35  cases  is  65  millimeters. 

Under  the  rebreathing  test  the  threshold  for  light  has  shown  an 
improvement  in  25.9  per  cent;  44.5  per  cent  show  neither  improve- 
ment nor  falling  off;  and  29.6  per  cent  show  a  falling  off  in  sensi- 
tivity. 

In  the  study  of  the  threshold  for  colors  the  red  and  green  both 
show  a  falling  off  in  71.4  per  cent  and  neither  a  gain  or  loss  in  26.6 
per  cent. 

In  former  tests  with  a  blue  light,  which  was  not  absolutely  mono- 
chromatic, there  was  improvement  in  66.6  per  cent  and  falling  off'  in 
33.4  per  cent. 

ACCOMMODATION  TEST  OBJECT. 

It  has  been  important  for  our  work  to  determine  the  best  possible 
test  object  for  determining  the  near  point  of  accommodation. 

The  object  of  these  tests  is  to  determine  the  comparative  value  of 
various  test  objects  used  in  determining  the  near  point  of  accommo- 
dation. Tests  were  also  made  to  determine  the  difference,  if  any, 
between  a  black  and  white  dot  in  determining  the  near  point  of  con- 
vergence.   The  objects  used  in  these  tests  were  as  follows: 

1.  Radiating  squares.  4.  Jaeger  type.  No,  1, 

2.  Illiterate  "  E."  5.  Duane  disk. 

3.  Numbers^.  6  Prince  rule. 

Two  separate  examinations  were  made  for  each  test  object. 
Twenty-five  men  were  examined,  and  a  general  average  gave  the  fol- 
lowing results  of  difference  in  readings 

Millimeter. 

Kadiating  squares 14| 

Illiterate  "E" ^ 

Numbers 5-| 

Jaeger,  No.  1 4^ 

Duane  disk 3| 


290  AIR  SEBVICE   MEDICAL. 

The  Duane  disk  is  wthe  best  test  object  for  general  use.  It  is 
found,  however,  that  during  the  rebreathing  test  it  is  difficult  for 
the  subject  to  quickly  recognize  the  faint  black  line  on  the  disk,  and 
the  later  readings  are  not  satisfactory.  Tests  of  black  and  white 
dots  in  finding  the  near  point  of  convergence  show  no  appreciable 
difference  between  them. 

As  Jaeger  type  is  not  standardized,  and  as  the  various  units  should 
have  some  standard  in  order  to  obtain  uniform  results,  a  plate  has 
been  made  with  two  sizes  of  standard  type.  This  type  is  made  up  of 
mixed  lettere  and  numbers.  The  smaller  type  is  0.6  millimeter  and 
the  larger  0.8  milimeter,  so,  should  the  accommodation  fall  off  late 
in  the  tests,  the  larger  type  can  be  seen.  Above  the  letters  is  a  black 
dot  for  use  in  determining  the  near  point  in  convergence,  thus  elim- 
inating a  certain  amount  of  delay  in  changing  cards  during  the  test. 

ASTIGMATISM. 

The  effect  of  lowered  barometric  pressure  and  lack  of  oxygen  upon 
astigmatism  has  been  tested  in  several  instances,  and  so  far  no  change 
has  been  shown  in  astigmatism  due  to  lack  of  oxygen  or  lowered  baro- 
metric pressure. 

EXAMINATION    OF    THE    FUNDUS    DURING    REBREATHING    AND    LOW    PRES- 
SURE  EXPERIMENTS. 

There  has  been  very  little  change  noted  in  the  fundus'  appearance, 
but  at  the  end  of  the  rebreathing  run  of  above  20,000  feet  in  the  low 
pressure  chamber  the  retinal  vessels  have  shown  some  congestion. 

IRIS   REACTION   DURING   REBREATHING   AND   LOW   PRESSURE   EXPERIMENTS. 

The  object  of  these  tests  is  to  determine  the  change  in  reactions 
of  the  iris  and  pupillary  diameters  during  rebreathing. 

Fifteen  men  were  examined  for  this  experiment  and  carried  from 
18,000  to  28,000  feet.  The  changes  were  not  altogether  uniform,  as 
certain  of  the  cases  reacted  more  strongly  to  light  than  to  accommo- 
dation, and  vice  versa.  Some  changes,  however,  seem  to  be  fairly 
constant. 

Below  10,000  feet  no  changes  are  noted;  above  this,  varying  in 
different  individuals  as  to  height,  there  is  an  increase  in  reflexes  for 
both  light  and  accommodation.  This  holds  until  late  in  the  experi- 
ment and  then  slowly  diminishes,  and  if  the  subject  is  allowed  to 
remain  on  the  machine  near  fainting  point,  reflexes  are  entirely 
abolished.  The  pupil  slowly  dilates,  usually  beginning  above  15,- 
000  feet  and  remains  so  during  the  remainder  of  the  experiment. 
If  allowed  to  remain  on  the  machine  too  near  the  fainting  point, 
the  pupil  is  quite  widely  dilated. 


AIR  SERVICE   MEDICAL.  291 

EFFECT  OF  TOBACCO   UPON   THE   EYE. 

The  problem,  as  taken  up  by  the  Ophthahnological  Department 
of  the  Medical  Research  Laboratory,  Hazelhurst  Field,  was  to  deter- 
mine what  effect,  if  any,  tobacco  has  upon  vision,  reaction  time,  reti- 
nal sensitivity,  accommodation,  and  convergence  of  habitues,  and 
nonsmokers.  Although  this  investigation  is  still  uncompleted,  it  is 
believed  that  a  preliminary  report  is  desirable. 

The  widespread,  increasing,  and  unrestricted  use  of  tobacco  in  the 
Army  and  Navy  furnishes  the  practical  incentive  and  justification 
for  the  investigation. 

APPARATUS  EMPLOYED  THUS  FAB. 

A.  For  visual  acuity:  (1)  Ives  apparatus  at  20  feet.  (2)  Snellen 
test  card.     (Unsatisfactory  and  abandoned  for  this  purpose.) 

Note. — 20/20  vision  is  equivalent  to  1.00  on  the  Ives  apparatus. 

B.  For  circulation  effects:  A  standard  sphygmomanometer,  stop 
watch,  and  stethoscope. 

C.  Accommodation  and  convergence  (near  point) :  The  Prince 
rule,  with  Jaeger  test  type,  and  a  2-millimeter  black  dot  on  a  white 
field. 

D.  Retinal  sensitivity  and  contract  sensitivity:  For  these,  the 
photometric  wedge  was  used,  employed  in  such  a  manner  as  to  blend 
within  a  period  of  5  to  8  seconds,  two  gray  squares,  one  within  the 
other,  differing  from  each  other  in  tint  by  13  perceptible  shades. 
The  squares  must  be  highly  illuminated  by  a  shaded  nitrogen  day- 
light lamp,  and  observed  at  a  distance  of  20  feet. 

TESTS. 

Visual  acuity :  This  was  very  carefully  taken  on  the  Ives  apparatus 
every  four  minutes  during  smoking,  after  having  previously  taken 
several  preliminary  observations  at  two-minute  intervals.  Where 
possible,  control  tests  lasting  a  half  hour  or  more  were  taken  later 
in  order  to  compare  the  regularity  of  the  curves  with  those  of  the 
tests  while  smoking.  Several  observations  were  made  after  the  sub- 
ject had  ceased  to  smoke. 

In  all  cases  vision  was  taken  separately  for  each  eye,  with  the  sub- 
ject wearing  his  usual  correcting  lenses.  Variation  of  the  direction 
of  the  lines  in  the  Ives  apparatus  was  tried  but  was  discontinued  as 
unsatisfactory  and  the  lines  were  maintained  in  one  position  during 
the  test  (generally  vertical).  This  was  to  avoid  variation  in  read- 
ings due  to  slight  astigmatic  errors. 

Blood  pressure. — This  was  taken  every  four  minutes  after  at  least 
three  preliminary  observations,  two  minutes  apart,  and  was  con- 
89118—19 20 


292  ATE  SEEVIOE  MEDICAL. 

tinued  until  the  cigar  was  consumed  with  one  or  more  final  observa- 
tions, two  to  four  minutes  afterwards.  The  systolic  and  diastolic 
pressure  was  taken  by  stethoscope  method. 

Pulse. — Normals  and  test  observations  at  four-minute  intervals. 

Convergence  and  accfimmodation. — These  were  taken  generally 
every  10  minutes,  as  was  also  retinal  sensitivity  to  contrast. 

Results. — Of  16  subjects  tested  and  their  records  charted  and  curves 
plotted,  results  are  as  follows : 

A.  Visual  acuity:  Twelve  (75  per  cent)  showed  a  fall,  the  average 
of  which  was  0.17  (Ives's  apparatus). 

One  (6  per  cent)  showed  a  rise;  three  (19  per  cent)  not  changed. 

Note. — Curves  showing  both  a  rise  and  a  fall  are  classed  accord- 
ing to  which  predominates.  A  slight  preliminary  rise  occurred  in 
nine  cases,  the  dominant  effect  of  which,  however,  was  a  fall.  The 
duration  of  lowered  vision  was  very  brief,  lasting  at  most  only  a  few 
minutes  after  cessation  of  smoking. 

B.  Systolic  and  diastolic  blood  pressure:  Both  were  affected  and 
in  general  similarly,  though  not  in  equal  degree.  Both  showed  a 
rise  of  69  per  cent  in  16  cases.  In  3  (19  per  cent)  there  was  a  fall  of 
the  systolic  and  4  (25  per  cent)  of  the  diastolic  pressure.  The  aver- 
age rise  of  the  systolic  was  9.3  millimeters,  of  the  diastolic  7  milli- 
meters. The  average  fall  of  the  systolic  was  8  millimeters,  of  the 
diastolic  5.5  millimeters.  Here  also  the  effect  was  temporary,  usu- 
ally lasting  but  a  few  minutes. 

C.  Pulse :  A  rise  in  pulse  rate  was  nearly  constant,  14  cases  out  of 
16  (87^  per  cent)  showing  an  increase,  the  average  of  which  was  14.3 
beats  per  minute.    Two  cases  showed  a  fall  averaging  five  beats. 

D.  Accommodation :  Of  13  subjects,  5  (38  per  cent)  showed  a  loss, 
this  loss  averaging  33  millimeters.  Two  showed  an  improvement 
averaging  12  millimeters;  6  (46  per  cent)  showed  no  change.  Those 
showing  the  greatest  loss  were  presbyopic. 

E.  Convergence:  Of  12  cases,  50  per  cent  showed  more  or  less 
falling  off;  5  (42  per  cent)  showed  no  change.  One  apparently 
improved  by  10  millimeters.  It  will  be  seen  that  the  effect  upon 
convergence  and  accommodation  was  much  more  uncertain  than  in 
the  cases  of  visual  acuity  and  blood  pressure.  The  same  may  be 
said  for  superduction  and  adduction  as  tested  by  prisms. 

F.  Retinal  contrastivity :  The  use  of  the  wedge  elicited  no  changes 
under  tobacco,  so  far  as  could  be  ascertained,  except  in  two  cases, 
which  showed  a  loss  of  10  millimeters. 

Conclusions :  Observations  to  date  indicate  that  approximately  75 
per  cent  of  smokers  have  definite  though  temporary  effects  upon 
vision  from  a  single  cigar,  and  almost  an  equal  proportion  show  a 
rise  in  blood  pressure,  while  there  is  an  increased  pulse  rate  in  nearly 


AIS  SEEVIOE  MEDICAL.  293 

90  per  cent.  This  effect  is  also  temporary,  although  John,  in  1913, 
reported  that  the  use  of  two  cigars  caused  a  rise  of  blood  pressure 
lasting  for  two  hours  after  the  cessation  of  smoking.  In  1907  Hesse 
found  similar  pressure  effects.  Nonsmokers  have  not  as  yet  been 
tested  in  numbers  to  afford  a  report.  Only  one  enters  this  series. 
He  showed  a  fall  of  0.3  in  visual  acuity.  Accommodation  fell  off 
15  millimeters.  There  was  apparent  reduction  in  retinal  contrastiv- 
ity  of  1  millimeter.  Some  giddiness  occurred  at  18  minutes  from 
start,  accompanied  by  slight  nausea. 

Aviation  medical  authorities  in  the  war  zone  have  remarked  that 
aviators  were  using  tobacco  excessively,  smoking  while  in  the  air  as 
well  as  incessantly  while  on  the  ground.  It  has  further  been  re- 
ported that  soldiers  on  the  western  front  have  frequently  complained 
of  night  blindness.  Some  of  these  cases  may  be  due  to  excessive 
tobacco  without  the  occurrence  of  a  typical  tobacco  amblyopia. 
Practically  the  same  results  as  have  been  obtained  by  smoking  one 
cigar  have  been  produced  by  the  inhalation  of  one  or  two  cigarettes. 

VI.— PSYCHOLOGY  DEPARTMENT. 

I.   TEDE  RELATION  OF  PSYCHOLOGY  TO  THE  AVIATOR. 

The  function  of  psychology  in  respect  to  the  aviator  is  to  study 
his  adaptability  to  the  work  required  of  him.  Assuming  that  the 
determinable  structural  qualifications  of  the  aviator  are  adequate, 
that  his  more  mechanical  physiological  functions  are  satisfactory,  it 
is  yet  necessary  to  determine  the  conscious  or  integrative  action  of  his 
organism,  with  regard  to  the  adaptations  which  contribute  to  the 
composition  of  a  good  flier;  and  further,  his  adaptability  to  one  or 
another  set  of  requirements  for  different  departments  of  the  flying 
work. 

Obviously,  these  determinations  may  be  made  by  the  trial  and 
error  method  (which  in  this  case  is  merely  a  survival  method),  and 
this  has  been  followed  to  a  large  extent  in  several  foreign  air  services. 
The  candidates  are  roughly  selected,  and  those  who  do  not  success- 
full}^  adapt  themselves  to  the  general  or  specific  requirements  prac- 
tically eliminate  themselves.  This  method  is,  however,  believed  to 
be  wasteful,  and  imdoubtedly  a  more  economical  method  can  be  suc- 
cessfully followed. 

The  contribution  which  psychology  can  make  to  the  efficiency  of 
the  Air  Service,  in  view  of  the  foregoing,  can  be  summarized  under 
eight  heads: 

1.  The  adaptability  of  the  individual  to  the  general  requirements 
of  the  service  may  be  determined.  Some  of  these  requirements  may 
be  enumerated  in  a  list  not  intended  to  be  exhaustive. 


294  AIR  SERVICE   MEDICAL. 

I.  Perception  (including  discrimination).  The  ability  to  perceive 
accurately  and  quickly  through  the  various  senses  (visual,  auditory, 
tactile,  muscular  and  articular,  and  visceral),  which  are  important 
for  the  flier,  depends  not  merely  on  the  perfection  of  the  sense  organs, 
but  also  on  the  integrative  action  by  which  definite  and  useful  per- 
ceptual reactions  are  achieved. 

II.  Control  of  "  voluntary "  activity,  i.  e.,  of  that  activity  which 
must  vary  in  its  expression  according  to  the  variations  in  the  environ- 
ment. Such  activity  is  truly  integrative  and  is  in  general  a  part  of 
the  perceptual  process. 

III.  Maintenance  of  equilibrium,  and  orientation.  The  complex 
mechanism  by  which  the  flier  preserves  his  balance,  and  the  more 
complex  mechanism  by  which  he  finds  his  way  about,  are  so  inter- 
connected that  they  necessarily  must  be  treated  together,  although 
the  functions  are  widely  different.  To  a  large  extent  these  f mictions 
are  automatic  (mechanical),  yet  both  involve  all  the  senses  enu- 
merated above  and  involve  in  both  cases  more  or  less  integration  of 
the  nervous  system. 

IV.  Memory  (in  the  sense  of  retentiveness)  is  dependent  on  con- 
ditions which  are  apparently  in  part  constitutional,  and  in  part  sub- 
ject to  control,  although  the  detailed  basis  of  these  conditions  is  not 
at  present  known. 

V.  Associative  thinking,  which  depends  on  retentiveness  and  ex- 
presses itself  in  the  various  forms  of  judgment,  inference,  and  de- 
cisions, is  an  integrative  function  closely  connected  with  perception, 
but  by  no  means  varying  directly  with  it  in  efficiency.  It  is  becoming 
more  and  more  clear  that  thinking,  like  perception,  is  a  conscious 
reaction  of  the  organism,  and  can  be  adequately  treated  only  as  such. 

VI.  Emotional  response :  Emotions  are  directly  connected  with  the 
driving  force  of  the  organism,  and  are  in  the  highest  degree  im- 
portant in  all  mental  processes.  The  Darwinian  point  of  view  of 
emotion  (as  developed  by  James,  Sutherland,  and  especially  by 
Lange),  that  it  is  a  bodily  (chiefly  viceral)  condition  or  process,  is 
more  and  more  becoming  indispensible  for  practical  consideration  of 
the  emotional  life. 

VII.  Attention,  which  is  the  direct  expression  of  the  degree  and 
completeness  of  integration,  is  of  especial  importance.  Not  only  the 
extent  to  which  the  flier  can  subordinate  all  other  reactions  to  the 
vital  reaction  of  the  moment,  and  the  length  of  time  during  which 
the  vitally  important  details  of  the  situation  which  confronts  him 
can  continue  to  dominate  his  nervous  system  in  spite  of  distractions 
(the  power  of  sustaining  attention,  as  we  commonly  express  it)  ; 
but  also  the  proper  balance  in  integration  (the  power  of  attending 
efficiently  to  several  distinct  details  in  a  situation),  need  to  be  studied 
very  carefully. 


AIR   SERVICE   MEDICAL.  295 

VIII.  Habit  formation,  or  learning,  which  is  the  modification  of 
the  integrative  system  (it  may  be  the  modification  of  perception  and 
motor  control,  or  of  thinking  process),  is  a  topic  of  especial  im- 
portance in  flying  and  is  one  concerning  which  psychologists  have 
acquired  a  large  amount  of  information  in  recent  years. 

A  knowledge  of  the  precise  requirements  for  the  flier  in  all  these 
directions  is  yet  to  be  obtained.  Various  opinions  have  been  ex- 
pressed as  to  the  requirements,  but  psychologists  are  unanimously  of 
the  opinion  that  any  conclusions  in  these  matters  should  be  reached 
by  systematic  observations  and  experiments.  In  this  laboratory 
work  on  these  problems  is  being  carried  on  by  men  who  have  so  far 
attained  results  which  are  distinctly  encouraging,  but  not  yet  in  a 
stage  where  the  communication  thereof  is  feasible. 

2.  The  adaptability  of  the  aviator  to  special  requirements  of  the 
different  departments  of  flying  work :  The  same  work  is  not  required 
of  observers  as  is  required  of  pilots,  and  bombing  and  combat  do  not 
require  exactly  the  same  sort  of  pilot  work.  The  list  of  special  quali- 
fications will  probably  grow,  as  aviation  develops,  but  so  far  little 
has  been  done  in  the  way  of  determining  and  measuring  the  special 
qualifications.  Work  has  been  undertaken  in  this  line  and  results 
will  be  forthcoming  in  due  time. 

3.  Special  conditions  to  which  the  flier  may  be  subjected :  Probably 
the  most  important  special  condition  is  the  combination  of  cold  and 
low  oxygen  tension  encountered  at  high  altitudes.  While  nothing  has 
yet  been  done  in  the  Medical  Research  Laboratory  on  the  temperature 
problem,  a  great  deal  has  been  done  on  effects  of  insufficient  oxygen 
supply.  In  addition  to  the  physiological  effects  of  asphyxiation, 
there  are  distinct  psychological  effects  which  have  been  carefully 
studied  by  the  psychology  section.  Although  we  have  recognized 
from  the  beginning  that  tests  for  asphyxiation  effects,  and  the  grad- 
ing of  fliers  on  the  basis  of  their  endurance  of  oxygen  deprivation, 
are  of  minor  importance  as  compared  with  tests  in  the  other  direc- 
tions indicated  above  (since  the  evil  effects  of  the  low  oxygen  tension 
of  the  upper  atmosphere  can  in  most  cases  be  obviated  by  administer- 
ing oxygen  to  the  flier),  nevertheless  it  was  necessary  to  get  this 
problem  out  of  the  way  before  other  problems  could  be  attacked. 
Full  details  of  the  psychological  tests  and  ratings  for  oxygen  short- 
age are  given  in  a  later  chapter. 

4.  Deterioration :  Assuming  that  the  individual  flier  is  fit  for  his 
job  and  properly  trained,  we  nevertheless  find  that  he  may  suffer 
deterioration,  both  of  a  temporary  sort  and  of  the  more  lasting  sort, 
which  is  frequently  designated  as  "  staleness."  The  fact  that  an 
individual  when  in  his  best  trim  is  a  high-class  flier  and  efficient  in 
his  especial  department  of  flying  does  not  promise  that  he  will  re- 


296  AIE  SEEVIOE  MEDICAL. 

main  such;  the  fact  that  an  individual  shows  high  capacity  for 
endurance  of  oxygen  shortage  does  not  signify  that  he  is  in  good 
flying  condition,  although  it  is  known  that  deterioration  in  certain 
conditions  requisite  for  flying  will  reduce  the  individual's  ability  to 
withstand  oxygen  shortage. 

Although  it  is  believed  that  in  certain  cases  psychological  causes 
(worry,  fear)  may  be  responsible  for  deterioration,  there  is  probably 
a  more  important  range  of  physiological  causes  operative.  In  all 
these  cases,  however,  mental  symptoms  are  produced,  since  it  is  pre- 
cisely in  the  failure  to  integrate  properly  rather  than  in  specific 
failure  of  sense  organ  or  muscles,  that  "  staleness  "  shows  itself.  The 
discovery  of  the  symptoms  and  the  development  of  tests  which  shall 
reveal  them  as  early  as  possible  is  undoubtedly  one  of  the  most  im- 
portant contributions  psychology  can  make  to  aviation,  since  it  is 
important  that  the  symptoms  be  detected  in  the  earliest  possible 
stage.  The  task  is  being  undertaken,  and  we  have  reason  to  be  con- 
fident it  will  be  successfully  carried  out  if  the  work  continues. 

From  the  foregoing  presentation  it  should  be  evident  that  a  num- 
ber of  diverse  problems  confront  us.  The  requisite  tests  of  general 
ability  and  of  special  abilities  must  be  worked  out  conjunctively,  but 
are  not  capable  of  combination.  Certain  of  these  tests  which  are 
capable  of  repetition  may  be  useful  in  determining  an  aviator's  con- 
dition (for  detecting  deterioration),  but  the  applicability  of  these 
or  any  other  tests  for  deterioration  must  be  worked  out  independ- 
ently. It  is  especially  important  to  note  that  psychological  tests 
for  endurance  of  special  conditions  (oxygen  shortage),  if  adequate 
for  their  purpose,  can  not  give  any  reliable  evidence  on  general  or 
other  special  qualifications  or  on  deterioration. 

II.     PSYCHOLOGICAL    RATING    OF    AVIATORS    FOR    ALTITUDE    LIMITS. 

OUTLINE   OF   CONDITIONS. 

The  work  on  oxygen  deficiency  has  so  far  been  principally  under 
the  conditions  established  by  the  rebreathing  apparatus,  with  some 
check  experiments  in  the  low-pressure  chamber.  With  this  appara- 
tus it  is  possible  to  produce  the  oxygen  tension  in  respired  air  equiva- 
lent to  the  tension  for  any  elevation  up  to  that  at  which  the  patient 
can  no  longer  endure  the  deficiency. 

The  chief  respiratory  differences  between  the  rebreathing  con- 
ditions and  those  actually  obtaining  in  the  upper  atmosphere  are 
(1)  the  greater  density,  (2)  the  greater  moisture  (practically  satu- 
ration), (3)  the  higher  temperature  of  the  air  in  the  rebreathing 
machine,  and  (4)  the  method  of  breathing,  through  the  mouth,  with 
the  machine.  While  it  is  possible  that  one  or  another  of  these  dif- 
ferences (most  probably  the  third)   may  make  a  difference  in  the 


AIR  SERVICE   MEDICAL,  297 

ca'se  of  prolonged  holding  of  the  patient  at  certain  altitudes,  for 
rapid  "  ascents"  (i.  e,,  passages  from  normal  to  low  oxj'^gen  tension), 
the  finst  two  differences  do  not  seem  important.  There  has  been  as 
yet  no  means  of  testing  the  contributory  effect  of  temperature,  and 
it  has  not  been  possible  to  make  a  sufficiently  thorough  comparison 
of  the  effects  of  rebreathing  with  those  of  the  low-pressure  chamber. 
The  discomfort  of  the  mouth  breathing  is  undoubtedly  important  in 
individual  cases,  and  hence  interferes  somewhat  with  the  adequate 
rating  of  the  aviators,  but  in  the  cases  of  experienced  subjects  is  a 
minor  matter  and  has  no  important  bearing  on  the  scientific  conclu- 
sions. 

PSYCHOLOGICAL   EFFECTS. 

The  psychological  effects  of  oxygen  deficieiicy. — ^The  effects  of  oxy- 
gen insufficiency  upon  the  psychological  process  have  been  from  the 
beginning  of  our  work  studied  empirically,  with  the  least  possible 
hypothetical  guidance.  A  wide  range  of  details  of  mental  life  have 
been  investigated,  the  order  and  method  of  investigation  being  prac- 
tically directed  by  the  working  tests  which  were  available  or  which 
we  have  been  able  to  devise.  Hence  our  results  are  capable  of  throw- 
ing a  light  on  the  fundamental  principles  of  psychology. 

These  results  square  distinctly  with  the  conception  of  psychological 
processes  as  integrative,  i.  e.,  as  dependent  on  the  integration  of  the 
central  nervous  system,  the  working  together  of  the  system  as  a 
whole,  rather  than  on  the  action  of  any  specific  parts  of  the  system. 

The  basic  and  important  psychological  effects  of  asphyxiation  are 
on  voluntary  coordination  and  attention.  Until  asphyxiation  reaches 
the  stage  in  which  the  integrative  mechanism  is  rapidly  approaching 
the  condition  of  complete  unconsciousness,  no  effects  are  demonstrable 
which  are  not  clearly  the  failure  of  the  one  or  the  other,  or  both,  of 
these  two  mental  factors.  In  the  prefinal  stages  perception  is  as  effi- 
cient as  the  muscular  control  of  the  sense  organs  and  organs  of  expres- 
sion and  the  power  to  attend  to  the  stimuli  permit.  Discriminative 
judgment,  likewise,  shows  no  falling  off  in  rapidity  or  accuracy  ex- 
cept as  impaired  motor  control  and  attention  produce  it.  Memory, 
with  "  immediate  memory,"  as  tested  by  the  ability  to  produce  what 
has  been  perceived  or  learned  immediately  before,  and  "true  mem- 
ory," as  tested  by  the  ability  to  produce  something  which  has  been 
"  latent "  for  a  certain  interval  after  being  learned  are  apparently  not 
affected  except  as  the  inability  to  attend  to  the  details  in  learning  or 
in  reproducing  or  inability  to  control  the  muscular  mechanism  of 
expression  may  enter. 

The  efficiency  of  limited  neuro-muscular  groups,  as  indicated  by 
dynamometer  tests,  is  not  impaired  in  the  prefinal  stages  of  asphj'^xia- 
tion.  • 


298  AIB  SERVICE  MEDICAL. 

As  instances  of  tests  involving  perception  and  discrimination,  we 
may  cite  the  copying  of  a  list  of  work  and  the  translation  of  words 
into  code.  In  both  of  these  cases  speed  and  accuracy  are  maintained 
up  to  the  final  stages  of  asphyxiation,  provided  the  muscular  mech- 
anism of  accommodation  and  convergence  are  not  seriously  affected, 
although  the  mechanism  for  handwriting  may  be  so  affected  that  the 
written  results  of  the  list  are  legible  with  difficulty. 

In  more  complicated  discrimination,  where  rapid  and  accurate 
recognition  and  classification  of  material  are  required,  the  results  are 
similar.  Ability  to  remember  and  to  chart  correctly  the  relative 
spacial  position  of  objects  remains  normal  .within  the  limits  of  ability 
to  make  adequate  movements  of  the  hand  in  charting. 

It  is  interesting  to  note  that  the  sensitivity  and  acuity  of  the  sense 
organs  shows  no  consistent  impairment  and  that  apparently  the  speed 
of  simple  reactions  (the  simple  reactions  do  not  in  general  require  a 
high  degree  of  integration)  is  not  intrinsically  reduced.  More  work 
remains  to  be  done  on  simple  reactions,  however,  before  definite  state- 
ments can  be  made.  The  distinctive  effect  on  the  nervous  system,  in 
short,  seems  to  be  a  change  in  its  integrative  action  and  not  a  change 
in  the  irritability  or  efficiency  of  any  particular  part  or  unit.  In  this 
respect  the  whole  picture  of  asphyxiation  from  a  psychological  point 
of  view  is  strongly  suggestive  of  the  picture  of  progressive  alcoholic 
intoxication. 

There  is  some  evidence  that  practice  in  enduring  asphyxiation  has 
value  in  increasing  the  efficiency  of  the  individual  under  a  certain 
degree  of  asphyxiation.  Expressed  in  untechnical  terms,  the  indi- 
vidual may  learn  to  husband  his  resources  and  by  applying  his  ca- 
pacity to  the  tasks  in  hand  accomplish  more  at  a  certain  level  than 
he  could  without  practice.  More  definite  statement  on  this  point 
can  not  be  made  on  the  basis  of  the  present  material.  It  is  not  pos- 
sible that  habituation  to  the  effects  of  alcohol  (not  to  regular  dos- 
ages) may  be  a  help  in  acquiring  ability  to  maintain  motor  and 
attention  efficiency  in  certain  degrees  of  asphyxiation. 

Training  of  another  sort  may  also  be  advantageous.  "  Grit "  counts 
in  the  maintenance  of  efficiency,  or  rather  the  maintenance  of  effi- 
ciency in  the  face  of  serious  oxygen  deficiency  is  "  grit,"  and  if  "  grit " 
in  one  task  or  situation  can  be  acquired  or  increased  by  training  in 
other  situations  (which  is  by  no  means  certain),  then  such  training 
is  advantageous. 

PEACTICAL  BEQUIBEMENTS. 

Under  the  practical  requirements  of  rating,  tests  must  be  single 
and  brief  during  progressive  depletion  of  the  oxygen  supply.  If 
many  individuals  are  to  be  examined  it  is  not  practicable  to  spend 
even  several  hours  on  each  one.    Hence  it  is  not  possible  to  hold  the 


AIR  SERVICE   MEDICAL.  299 

subject  at  a  moderately  high  altitude  so  that  asphyxiation  effects- 
will  eventually  appear.  Nor  is  it  possible  to  repeat  a  briefer  test  a 
number  of  times.  Hence,  the  subject  must  be  allowed  to  rebreathe 
rapidly  (during  not  much  over  a  half  hour  at  most),  to  a  low  point 
of  oxygen  tension,  reaching  his  maximal  altitude  for  that  rate  of 
"  ascent."  It  follows  that  the  method  used  must  be  one  which  is  not 
approved  for  psychological  work  under  other  conditions  and  which, 
for  want  of  a  better  term,  is  called  clinical.  Thus,  since  the  sub- 
ject's condition  is  rapidly  changing  from  minute  to  minute,  the  ex- 
aminers must  be  able  to  determine  the  psychological  condition  at  any 
minute  and  can  not  use  the  method  (more  exact  under  other  condi- 
tions) of  determining  the  average  speed  and  accuracy  of  work  done 
during  a  period  of  several  minutes. 

A  final  composite  reason  for  using  a  clinical  method  comes  from 
the  need  for  rapid  work.  Graphic  methods  might  be  employed,  but 
would  largely  hinder  the  expedition  of  the  work  on  account  of  the 
time  and  labor  needed  for  their  interpretation.  Moreover,  in  such 
rapid  work  fineness  of  gradation  in  rating  would  be  seriously  mis- 
leading, hence  the  greater  exactness  of  the  graphic  method  would  be 
largely  illusory.  For  research  purposes,  on  the  other  hand,  the  mat- 
ter is  entirely  different. 

Fatigue,  also,  must  enter  into  the  test  as  little  as  possible,  else  the 
deterioration  in  performance  due  to  fatigue  will  confuse  the  de- 
termination of  the  asphyxiation  effects. 

Since  the  test  can  not  be  repeated,  it  is  important  that  there  shall 
be  little  practice  effect  in  the  work  required,  else  the  individual 
variation  in  rates  of  learning  will  prevent  the  fair  determination  of 
the  relative  susceptibility  of  the  different  subjects  to  the  oxygen 
deprivation,  which  is  the  sole  point  to  be  considered. 

It  was  early  discovered  that  under  asphyxiation,  as  under  alcoholic 
intoxication,  it  is  possible  for  a  reactor  to  "  pull  himself  together  " 
for  a  brief  space  of  time  (a  minute,  or  even  several  minutes),  during 
which  his  efficiency  on  a  set  task  may  be  as  high  as  (or  even  higher 
than)  his  normal,  at  the  termination  of  the  task  sinking  to  a  relatively 
low  level  of  efficiency.  If  given  a  series  of  tasks,  with  brief  resting 
intervals  between,  the  reactor  may  therefore  accomplish  a  perform- 
ance which  is  practically  normal,  even  up  to  a  minute  or  two  before 
the  point  at  which  complete  lapse  of  integration  occurs.  In  this  way 
his  real  psychological  deterioration  may  be  masked.  It  is  necessary, 
therefore,  to  set  a  task  which,  although  minimally  fatiguing,  is  prac- 
tically continuous,  allowing  the  reactor  no  expected  periods  in  which 
no  work  will  be  demanded  of  him,  and  thus  preventing  him  from 
making  use  of  attention  peaks  as  the  phases  of  "pulling  himself 
together  "  may  justly  be  called. 


300  AIE  SEEVICE  MEDICAL. 

In  determining  the  sensitivity  or  acuity  of  sense  organs,  on  the 
other  hand,  the  "  attention  peaks  "  are  precisely  in  order,  and  pause 
should  be  taken  to  present  the  stimuli  at  the  highest  peaks. 

Many  tests  which  otherwise  would  be  applicable  impel  the  subject 
(reactor)  to  hold  his  breath  during  the  crucial  moments  of  the  test. 
The  conventional  steadiness  test  is  of  this  character.  If  the  reactor, 
already  suffering  from  oxygen  deficiency,  holds  his  breath  for  20 
seconds,  or  largely  reduces  his  breathing  during  that  period,  he 
makes  an  important  change  in  his  oxygen  supply,  a  change,  more- 
over, which  can  not  be  measured.  Hence  the  purpose  of  the  test  is 
largely  defeated.  The  steadiness  test,  and  others  in  this  class,  which 
may  show  marked  effects  of  low-oxygen  tension,  can  not  be  used. 

Although  it  is  desirable  that  the  test  employed  shall  in  some  degree 
correspond  to  the  aviator's  actual  task  in  flying,  it  is  important  that 
it  shall  not  use  any  of  the  movements  or  discrimination  involved  in 
flying,  else  it  would  be  impossible  to  rate  fairly  both  those  with  and 
without  experience  in  planes. 

A  final  composite  reason  for  using  a  "  clinical "  method  comes  from 
the  need  for  rapid  work.  Graphic  records  might  be  employed,  but 
would  largely  hinder  the  expedition  of  the  work  on  account  of  the 
time  and  labor  needed  for  their  interpretation.  Moreover,  in  such 
rapid  work  fineness  of  gradation  in  rating  would  be  seriously  mis- 
leading, hence  the  greater  exactness  of  graphic  methods  would  be 
largely  specious.  For  experimental  work  the  matter  is  entirely 
different. 

In  addition  to  general  limitations  of  method  and  apparatus  due 
to  necessary  working  conditions,  there  are  specific  limitations  im- 
posed by  the  rebreathing  apparatus  and  the  cardiovascular  work 
which  must  be  simultaneous  with  the  psychological. 

I.  The  reactor  can  not  speak  on  account  of  the  mouthpiece.  This 
excludes  such  tests  as  the  association  reaction,  which  otherwise  might 
be  highly  useful. 

II.  The  reactor's  head  movements  are  narrowly  limited  and  his 
field  of  view  correspondingly  restricted.  This  is  not  a  very  serious 
limitation. 

III.  The  blood  pressure,  which  is  taken  throughout  the  test,  is 
taken  from  the  reactor's  left  arm.  This  further  limits  the  reactor's 
means  of  expression  to  one  arm  and  his  feet. 

APPARATUS  FOR  THE  STANDARD  TEST. 

The  apparatus  used  for  the  psychological  tests  consists  of  two 
groups,  (a)  and  (&).  The  (a)  group  includes  a  number  of  pieces 
assembled  on  a  specially  designed  table,  adjustable  in  height  and 
slope,  and  swinging  on  a  single  heavy  post  mounted  on  a  cast-iron 
base.    This  table  is  designed  to  furnish  a  sufficiently  rigid  mounting 


IT'  *"    '    I 


■■*'** -.■^■'' 


T 


171 


AIR  SERVICE  MEDICAL.  301 

and  at  the  same  time  give  greater  convenience  than  could  be  afforded 
by  a  table  with  legs. 

(a)  The  apparatus  mounted  on  the  table  form  three  separate  units, 
(1)  a  series  of  14  stimulus  lamps  (2  c.  p.)  arranged  in  two  rows  of 
seven  each,  with  two  similarly  arranged  rows  of  contact  buttons; 
each  surrounded  by  a  washer;  a  green  check  lamp  and  a  red  error 
lamp ;  and  a  stylus  with  a  hard  rubber  han^lle  and  metal  tip.  These 
parts  of  the  unit  are  so  wired  electrically  that  when  a  stimulus  lamp 
lights  the  corresponding  contact  button  is  "  alive,"  and  if  touched 
with  the  metal  tip  of  the  stylus  causes  the  check  lamp  to  light.  If 
the  washer  surrounding  any  of  the  buttons  is  touched  with  the  stylus 
at  any  time,  the  error  lamp  lights. 

(2)  Two  ammeters  mounted  on  a  metal  arm  above  the  table  top 
are  connected  in  series  with  two  rheostats,  one  on  the  upper  side 
of  the  table  top  at  the  edge  nearer  the  reactor,  the  other  underneath, 
at  the  edge  nearer  the  psychologist.  One  ammeter  faces  the  reactor, 
the  other  the  psychologist.  A  change  in  the  resistance  made  by  the 
psychologist  at  his  rheostat,  causing  a  change  in  the  ammeter  reading, 
may  be  compensated  for  by  a  change  in  the  reactor's  rheostat,  by 
which  the  original  ammeter  reading  may  be  restored. 

(3)  A  small  electric  motor  mounted  on  the  upper  side  of  the  table 
top  is  connected  in  series  with  a  third  rheostat  underneath  the  table. 
A  two-way  lever  switch  mounted  underneath  the  table  at  the  edge 
next  to  the  psychologist  and  a  rocking  pedal  two-way  switch  on  the 
floor  under  the  table  are  connected  with  the  rheostat  by  a  three-wire 
system,  so  that  a  part  of  the  resistance  of  the  rheostat  can  be  cut 
out  (thus  increasing  the  speed  of  the  motor)  by  either  switch  and 
again  cut  in  (thus  restoring  the  lower  motor  speed)  by  either  switch. 

(&)  The  second  group  of  apparatus,  on  a  small  table  in  any  con- 
venient part  of  the  room,  consists  of  either  a  button  board  having  14 
buttons,  corresponding  to  the  14  stiniulus  lamps,  or  of  an  automatic 
distributor  which  lights  the  stimulus  lamps  in  selective  order  and 
times  their  duration.  With  the  button  board  an  automatic  flash 
timer  may  be  used,  requiring  an  assistant  merely  to  select  the  buttons, 
or  the  assistant  may  time  the  flasher  with  a  stop-watch  as  well  as 
select  the  buttons. 

The  (a)  and  (h)  groups  of  apparatus  are  provided  with  trans- 
formers to  adapt  the  electric  current  to  the  2  c.  p.  lamps,  and  are 
electrically  connected  with  either  and  with  the  source  of  120  volt 
a.  c.  current  by  flexible  cables. 

Method  of  conducting  the  test.  The  rebreathing  machine  should 
be  adjusted  by  the  physiologist  to  give  a  "  standard  run,"  which  will 
vary  in  time  according  to  the  individual  and  his  method  of  work, 
but  which  will  bring  a  reactor  of  the  A  class  to  7  per  cent  of  oxygen 


302  AIB  SERVICE  MEDICAL. 

in  25  minutes  on  the  average.     For  this  standard  run  the  quantity 
of  air  in  the  tank  at  start  is  60  liters. 

The  reactor,  being  seated  in  proper  position  before  the  (a)  appa- 
ratus, is  given  the  following  instructions  in  printed  form : 

INSTRUCTIONS. 

BEAD    CAEEFOIXY. 

You  have  three  things  to  do: 

1.  Lights. 

When  a  light  flashes,  touch  with  the  stylus  the  top  of  the  corresponding  button. 
Do  not  touch  the  washer. 

2.  Ammeter. 

Watch  the  ammeter  and  by  adjusting  the  slide  of  the  rheostat  (using  the 
right  hand)  keep  the  ammeter  at  the  designated  mark. 

3.  Motor. 

Keep  the  motor  at  low  speed  by  maintaining  the  proper  positions  of  the 
pedal.  AVhen  the  motor  speeds  up,  push  the  pedal  from  whichever  position  in 
which  it  may  be  (heel  down,  or  toe  down),  into  the  opposite  position,  and  leave 
it  in  the  new  position  until  the  speed  again  increases. 

Notes. —  (a)  The  lights  are  of  first  importance,  i.  e.,  if  a  light  appears  when 
you  are  reacting  (or  about  to  react)  to  the  ammeter-hand,  react  to  the  light 
first  and  then  go  back  to  the  rheostat. 

( 6 )  When  you  touch  with  the  stylus  a  contact-button  corresponding  to  a  light, 
the  movement  of  hand  and  arm  should  be  a  "free"  one  (neither  arm  nor  hand 
should  touch  table,  rheostat,  or  board).  The  hand  may,  at  other  times,  rest  on 
the  slide  of  the  rheostat. 

(c)  Do  your  work  with  accueacy,  neatness,  and  pbomptness.  Do  not  bang, 
slam,  or  jab. 

While  the  reactor  is  reading  the  instructions,  the  psychologist  is 
ready  to  explain  any  detail  of  ttie  apparatus  or  method  in  which  the 
reactor  may  show  interest;  and  after  the  reactor  has  finished,  the 
psychologist  further  explains  the  procedure  and  verbally  emphasizes 
the  important  points  in  the  instruction. 

When  the  rebreathing  machine  is  ready  and  the  blood-pressure  re- 
corder has  secured  the  requisite  preliminary  readings,  the  mouth- 
piece and  nose  clip  being  in  place,  the  external  opening  of  the  mouth- 
piece is  closed  by  the  responsible  clinician  and  the  test  commences. 
The  psychologist  and  all  others  concerned  in  making  the  test  start 
their  stop  watches  at  the  moment  when  the  rebreathing  commences. 
The  psychologist  should  record  if  possible  the  time  which  elapses 
between  the  insertion  of  the  mouthpiece  and  the  commencing  of 
the  breathing,  unless  a  regular  routine  for  this  time  be  adopted. 

During  the  first  three  minutes  of  the  test  the  ps3^chologist  coaches 
the  reactor  if  necessary  and  estimates  his  comprehension  of  the  task 


■ 

^^^^^^^L      il!^£:i^^tfP^~    J                   'J 

j^^^^^^^l 

^^^^^r 

^^^^I^^^^^^^^^^H 

AIR  SERVIOE   MEDICAL.  303 

and  instructions,  his  power  of  attention,  and  his  composure  (free- 
dom from  excitement  or  nervousness),  entering  these  on  the  record 
sheet  then  or  later  as  good,  fair,  or  poor.  He  should  also  note  the 
motor  tendencies  of  the  reactor,  and  if  these  fall  in  one  or  more  of 
the  following  categories  this  also  should  be  entered. 

MOTOB   TENDENCIES. 

To  be  put  on  original  record  slieet  at  bottom;  on  official  sheet  under  general 
impressions,  psychological ;  on  psychology  record  card  under  notes: 

(1)  Tremor. 

(2)  Tense. 

(3)  Impulsive. 

(4)  Steady. 

(5)  Rapid. 

(6)  Slow. 

(7)  Hesitant. 

(8)  Accurate. 

(9)  Inaccurate. 

(10)    (Combinations  of  above.) 
Enter  merely  the  appropriate  type  word  or  words;  it  is  not  necessary  to 
write  "  motor  tendencies." 

In  addition  to  these  general  tendencies,  it  is  important  that  the 
psychologist  take  notice  of  the  specific  tendencies  shown  by  the  re- 
actor, and  if  definite  types  of  error  are  shown,  watch  during  the 
succeeding  five  or  six  minutes  for  improvements  in  these  details.  In 
this  way  the  "  M  "  and  "A"  determination  described  below  may  be 
accurately  noted  as  deterioration  from  the  normal  proficiency  of  the 
reactor,  and  not  as  failures  with  regard  to  an  absolute  standard. 
This  is  important,  since  the  rating  on  these  tests  is  valid  only  as  an 
index  of  the  effects  of  asphyxiation  and  not  as  an  index  of  effi- 
ciency or  inefficiency  in  any  other  respect.  The  comprehension,  at- 
tention, composure,  and  motor  entries  are,  however,  worth  record- 
ing in  order  that  this  data  may  be  used  later  for  purposes  other 
than  oxygen  rating. 

Normally  the  test  continues  until  complete  inefficiency  is  reached, 
at  which  point  the  psychologist  must  sharply  notify  the  responsible 
medical  attendant  in  order  that  the  reactor  may  at  once  be  given  air, 
and  so  prevented  from  undergoing  the  collapse  which  would  ensue  in 
a  minute  or  so. 

The  recognition  of  complete  inefficiency  is  a  matter  on  which  the 
psychologist  must  carefully  train  himself.  In  general  it  shows  in  a 
definite  way,  as  described  below,  but  may  show  in  forms  which 
are  readily  recognized  by  the  trained  observer  but  described  with 
difficultv. 

In  many  cases  the  responsible  medical  attendant  will  find  it  neces- 
sary to  stop  the  test  because  of  dangerous  cardiovascular  symptoms 
before  inefficiency  is  reached. 


304  AIR  SEKVIOE  MEDICAL. 

In  commencing  work  on  the  reactor  it  is  advisable  to  allow  him 
to  react  to  the  lights  alone  during  the  first  minute  and  add  suc- 
cessively the  changes  in  the  motor  noise  and  in  the  ammeter  read- 
ings. He  should  be  working  on  all  three  tasks  by  the  middle  of  the 
third  minute. 

In  observing,  the  psychologist  needs  to  attend  as  constantly  as 
possible  to  the  behavior  of  the  reactor,  and  hence  must  reduce  the 
labor  of  recording  to  a  minimum.  For  this  purpose  and  for  the 
purpose  of  standardizing  the  method  of  observation  the  following 
symbols  have  been  adopted : 

SYMBOLS   AND  THEIR   SIGNIFICANCE. 

— >  Kebreathing  starts. 

W  Work  begins. 

"^  First  significant  effects  on  "voluntary  coordination." 

^  " Fumbling " ;  clumsy;  inaccuracy  in  touching  targets. 

0  "  Groping  " ;  approaching  target  with  corrective  move- 
V  ments.     Usually  a  compensation  for  9. 

E       Increased  ''effort"  or  force  in  applying  stylus  to 

targets. 
3       Decreased  effort. 

1  "Impulsive"  or  uncontrolled  movements: 

a,  on  the  outward  movement;  to  the  target. 

b,  on  the  return  movement. 
S       Slowing  of  reactive  movements. 

F       Speeding  of  reactive  movements. 
^      First  significant  effects  on  "attention." 
•   ,         dl      "Distraction"  from  lights,  neglects  lights. 
dL-v-    Neglects  lights  for  voltmeter. 
/       (Contraction  for  dtl.)     Reactor    delays    initiating 
stylus  movement  so  long  that  he  fails  to  light 
check  lamp. 
//      Reactor  delays  so  long  that  he  touches  the  target 

after  light  has  gone  out. 
/  /  /      Reactor  starts  movement  after  light  has  gone  out. 
/  /  /  /     Reactor  makes  no  attempt  to  initiate  light  reaction. 
clop      "Distraction"  from  the  dial;  neglects  to  note  and 

adjust  the  position  of  the  index  hand. 
dUv      "Distraction"  from  the  noise;  neglects  to  control  the 

speed  motor. 
/  CX  /    Confusion  between  rows  of  lamps;  but  finally  touches 
the  right  target. 
Ql      Confusion  between  columns  of  lamps;  but  finally 
touches  the  right  target. 
/uj-l/    Selecting  target  in  vrrong  row. 


AIB  SEEVIOE  MEDICAL.  305 

u>t      Selecting  target  in  wrong  column. 
Wv      Wrong  direction  on  the  dial. 
Wn     Wrong  shift  of  pedal. 

<^     Two  of  the  symptoms,  ^,  9,  I,  and  E,  repeatedly. 

In  certain  cases,  exaggeration  of  one. 
<3>      Two  of  the  symptoms,  dl,  cU>,  cUv,  ///,  /^/,  CI, 
Zv.     In  certain  cases,  exaggeration  of  one. 

O  "Inefficiency."  InabiUty  to  control  any  of  the  three 
tasks.  The  reactor  sometimes  stares  at  the  lights 
without  making  any  attempt  to  touch  the  target; 
or  makes  merely  irrelevant  touches.  Completely 
disregarding  L  and  N.  Sometimes  he  develops 
severe  tremors  or  jerks  which  render  it  impossible 
to  work.  Occasionally  a  reactor  develops  im.ique 
symptom  at  this  point. 

5|c  Breakdown.  Reactor  ceases  to  work  and  commences 
to  collapse.  This  comes  very  soon  (30''  to  2') 
after  0;  is  qualitatively  a  much  more  serious  con- 
dition. 

^      Reactor  ''taken  off."     Air  or  oxygen  given  him. 

ADDITIONAL  SYMBOLS  FOR  SYMPTOMS  WHICH  MAY  BE   OF  DIAGNOSTIC 

AED. 

\y\j^   Tremor  of  the  hand. 
'AJAA'    Jerkiness  of  the  hand. 
H       Swaying  or  drooping  of  the  head. 
T       Taps  button  more  than  once. 
R      Rests  hand  or  fingers  while  touching  button. 
K      Keeps  stylus  on  button  after  making  touch. 
In  general,  the  "arrowheads''  i-^)  and  "diamonds"  (0)  are  not 
inserted  until  after  the  test  is  finished. 

On  the  completion  of  the  test  the  entries  on  the  record  sheet  are 
completed,  and  the  material  is  now  ready  for  rating,  which  is  done 
on  the  following  basis : 

RATING  SCHEME, 

1.  Take  25  minutes  as  the  standard  duration  of  a  run.  If  the  O  or  X 
appears  before  the  end  of  25  minutes,  debit  one  point  for  each  minute ; 
similarly,  credit  one  point  for  each  minute  in  case  O  or  X  appears 
after  25  minutes. 

2.  Assume  as  a  standard  of  altitude  7  per  cent  of  oxygen  for  O  or 
X.    Debit  or  credit  one  point  for  each  -^  of  1  per  cent. 

3.  As  in  the  case  of  1,  take  25  minutes  as  the  standard  time  for  the 
appearance  of  both  of  the  two  diamonds.  Debit  or  credit  one  point 
for  each  minute  as  above. 


306  AIE  SERVICE   MEDICAL. 

4.  Assume  15  minutes  as  the  standard  time  for  the  appearance  of 
both  the  two  arrowheads.    Debit  or  credit  for  each  minute  as  above. 

5.  If  the  record  of  the  subject  tested  be  such  that  either  arrowhead 
or  either  diamond  can  not  be  entered,  compute  the  symbol  in  question 
as  if  it  fell  at  the  point  of  O  (or  X,  if  O  be  not  reached;  see  para- 
graph 6,  below). 

6.  Add  the  debits  and  credits,  and  assign  to  class  as  follows : 

+n 0  Class  A+ 

0 —12  Class  A— 

—12 —30  Class  B 

—30 — n  Class  C 

7.  Where  an  oxygen  tension  of  8  per  cent  or  less  is  not  attained  in 
less  than  30  minutes,  a  grade  above  B  shall  not  be  assigned.  For 
runs  reaching  a  low  percentage  (below  7  per  cent)  in  less  than  22 
minutes,  discretion  may  be  exercised  in  debiting  for  earliness  of 
symbols.    Such  short  runs  are  especially  to  be  avoided  if  possible. 

8.  For  a  definite  rating  O  must  be  used.  However,  in  case  the  test 
was  stopped  by  the  clinician  without  reaching  O,  the  tentative  rating 
may  be  computed  from  X.  If  this  tentative  rating  is  A,  it  is  to  be 
entered  as  such.  If,  however,  the  tentative  rating  is  of  a  lower  class, 
it  is  to  be  entered  with  the  addition  "  or  higher."  This  phrase  "  or 
higher"  shall  always  indicate  that  the  reactor  was  removed  before 
reaching  (O),  and  not  at  the  instance  of  the  psychologist.  It  is 
not  to  be  entered  in  any  other  case. 

On  first  glance*  the  rating  scheme  seems  to  be  based  on  time  rather 
than  on  oxygen  percentage,  but  this  is  only  apparent.  If  every  re- 
actor was  run  through  at  the  same  rate,  for  example,  a  rate  of  oxygen 
depletion  at  which  7  per  cent  would  be  reached  in  25  minutes,  it 
would  be  immaterial  whether  the  oxygen  percentages  or  the  times  at 
which  the  arrowheads,  diamonds,  and  circles  are  reached  should  be 
used,  since  there  would  be  a  fixed  correspondence  between  these. 
Since  rates  vary  in  accordance  with  the  individual  rates  of  oxygen 
consumption,  and  since  a  faster  rate  enables  the  reactor  to  reach  a 
lower  percentage,  and  a  slower  rate  brings  inefficiency  at  a  higher 
percentage-  it  is  necessary  to  make  allowance  for  the  variations  in 
rate.  This  can  be  done  either  by  computing  in  oxygen  percentages, 
and  then  making  a  correction  for  the  time,  or  more  simply,  as  in  the 
scheme  actually  employed,  by  computing  in  times,  as  if  the  oxygen 
change  followed  a*  line  of  the  same  slope  in  each  case,  and  then  cor- 
recting for  deviation  from  this  slope  in  terms  of  the  final  oxygen 
percentages  reached. 

The  rating  scheme  is  adequate  to  classify  the  reactors  in  the  four 
groups  (A-plus,  A-minus,  B,  and  C),  provided  the  psychologist  who 
does  the  observing  also  does  the  rating,  and  exercises  due  judgment, 
based  on  his  general  observation  of  the  reactor's  work,  in  rating  those 


AIR   SEBVICE    MEDICAL.  307 

cases  which  lie  near  the  limits  of  the  several  classes.  The  scheme 
should  be  an  assistance  to  the  psychologist's  final  judgment,  not  a 
hampering  condition,  although  the  most  satisfactory  results  will  be 
obtained  bv  relying  on  it  very  substantially. 

The  chief  difficulty  uith  this  method  of  testing  is  in  the  heavj»and 
exhausting  hibor  entailed  on  the  psychologist.  Necessarily  his  atten- 
tion is  kept  at  a  high  level  throughout  the  test,  and  it  has  already  be- 
come evident  that  a  full  daily  program  will  not  be  possible  as  a  con- 
tinuous thing.  It  is  hoped  that  it  will  be  possible  to  supply  two 
psychologists  with  each  testing  unit  of  which  heavy  duty  is  required, 
in  order  that  they  may  relieve  each  other  and  maintain  the  efficiency 
of  the  unit. 

In  making  the  test,  diligent  care  must  be  exercised  to  prevent  the 
reactor  from  being  anxious  or  alarmed  as  to  the  experience  he  is  to 
undergo.  Hence  no  remarks  must  be  made  in  his  presence  as  to  dan- 
ger or  serious  discomfort,  and,  if  necessary-  assurance  should  be 
given  that  the  test  makes  no  great  demands  on  the  reactor.  It  is 
also  important  that  instructions  be  given  in  a  routine  way,  the  same 
for  all  reactors;  otherwise  the  purposes  of  the  test  as  a  relative  rating 
scheme  are  in  part  defeated. 

The  temporary  physical  condition  of  the  reactor  is  also  a  matter 
which  should  be  carefully  considered.  Loss  of  sleep,  worry,  dissipa- 
tion, or  other  causes  which  reduce  general  resistance  are  apt  to  re- 
duce the* capacity  for  endurance  of  oxygen  deficiency,  and  produce  an 
earlier  onset  of  psychological  inefficiency  than  would  occur  under 
better  conditions. 

On  the  other  hand,  the  reactor  may  be  in  bad  shape  physically  or 
mentally  (from  worry,  etc.)  and  yet  make  a  very  good  record.  One 
reactor,  for  example,  who  made  an  unusually  good  record,  with  fine 
motor  control  and  efficient  attention  down  to  a  low  percentage  of 
oxygen,  had  had  but  a  few  hours  sleep  in  48  hours,  felt  in  "  rotten '' 
shape,  and  expressed  himself  anxious  to  come  back  when  he  felt  bet- 
ter, "  to  see  what  he  really  could  do  on  the  test." 

In  short,  the  test  gives  a  measure  of  endurance  of  oxygen  deficiency 
solel}'.  and  while  this  endurance  may  be  affected  by  a  variety  of 
factors,  it  gives  no  measure  of  these  factors. 

Some  incidental  results  of  the  v:ork  on  rehreathing. — It  is  apparent 
that  a  great  deal  which  has  come  to  light  in  the  course  of  the  work 
will  be  of  value  for  work  more  or  less  closely  allied.  Findings  in 
regard  to  the  precise  effect  of  oxygen  shortage,  and  the  conceahnent 
of  these  effects  through  "  attention  peaks  "  point  to  an  application, 
with  a  possibility  of  clearing  up  certain  puzzling  results  of  earlier 
work.  The  same  application  may  be  made  in  studies  of  fatigue, 
in  which  in  the  past  no  great  success  has  been  attained  with  psycho- 
89138—10 21 


308  AIR  SERVICE   MEDICAL. 

logical  tests.    Alcohol  and  drug  effects  may  also  be  attacked  anew 
in  the  light  of  the  present  work. 

The  relation  of  certain  emotional  states  to  systolic  pressure  has 
also  appeared  in  an  interesting  way.  The  conspicuous  thing  which 
has  flcome  out  is  that  apprehension — the  feeling  which  can  be  de- 
scribed as  "now  we  are  off;  I  wonder  just  what  will  happen  to 
me" — is'  associated  with  a  temporary  rise  in  systolic  pressure. 
Observation  in  these  effects  in  rebreathing  led  us  to  experiment 
with  various  expected  stimuli  (pretended  doses  of  drugs,  threatened 
stimuli  of  undescribed  kinds)  with  quite  uniform  results.  Where 
fear  enters,  the  systolic  rise  tends  to  be  sustained.  An  interest- 
ing series  of  observations  has  been  started  on  the  systolic  effect 
of  announcing  to  cadets,  waiting  on  the  field  for  instruction,  their 
turns  for  flight.  It  is  possible  that  very  practical  results  may  be 
obtained  in  this  way,  in  information  concerning  the  temperament  of 
the  cadets. 

III.  THE  PSYCHOLOGICAL  QUALIFICATIONS  OF  THE  FLIER. 

It  was  pointed  out  above  that  the  flier  needs  not  only  to  fly,  but 
also  needs  to  be  able  to  perform  definite  tasks — observing,  signaling, 
operating  a  machine  gun,  etc. — without  which  the  ability  to  pilot 
a  plane  would  be  of  little  military  use.  It  is  desirable,  therefore, 
to  determine,  in  so  far  as  it  may  be  possible,  the  aptitude  of  the 
candidate  for  the  acquisition  (in  the  ground  school)  of  the  funda- 
mental training  which  may  fit  him  for  the  required  range  of  work, 
and  to  determine  his  capacity  for  learning  and  performing  ade- 
quately the  tasks  for  which  the  ground  school  work  is  intended  to 
fit  him. 

To  a  certain  extent  a  survey  of  the  candidate's  school  and  college 
training  is  a  means  for  the  determination  of  his  possibilities,  since 
the  specific  sorts  of  training  he  has  already  received  are  thereby 
revealed,  and  since,  moreover,  such  schooling  is  in  itself  a  process 
of  elimination  of  those  who  are  not  intelligent  and  adaptable.  This 
method  of  determination  might  well  be  supplemented  by  "  intelli- 
gence tests  "  of  the  customary  type ;  but  even  these  additions  would 
not  take  the  place  of  specific  tests  of  the  functions  which  are  known 
to  be  important  in  flying. 

The  important  problem  is  the  discovery  of  the  tests  which  shall  be 
practicable.  The  plan  which  we  have  followed  in  this  work  is,  first, 
to  develop  tests  which  promise  to  be  applicable  to  the  aptitudes  it  is 
desired  to  investigate;  and  second,  to  give  the  tests  so  developed  to  a 
large  number  of  fliers  whose  actual  flying  ability  can  be  definitely 
known.  By  comparison  and  correlation  of  the  results  of  the  tests 
with  the  actual  efficiency  ratings  of  the  fliers,  it  is  possible  to  deter- 


ATB   SERVICE   MEDICAL.  309 

mine  the  applicability  and  usefulness  of  the  tests.  In  some  cases  the 
development  of  the  test  itself  is  a  difficult  experimental  undertaking; 
in  other  cases  the  tests  are  easily  obtained,  requiring  merely  the  ap- 
plication and  correlation. 

Evidence  of  flying  ability  is  obtained,  for  the  purpose  of  compari- 
son with  the  results  of  the  tests,  from  the  men  who  have  trained 
the  fliers  tested,  and  have  observed  their  irrdividual  progress  in  the 
work  of  aviation.  The  value  of  any  test  of  a  specific  function  which 
may  be  important  for  aviation  must  ultimately  rest  solely  on  this 
comparison.  No  theoretical  considerations  of  the  qualifications  of  a 
flier  can  be  substituted  for  the  empirical  determination  of  the  relative 
flying  abilities  of  men  differing  in  respect  to  the  qualifications  in 
question. 

Experimental  work  on  the  problem  of  flying  qualifications  has  been 
done  at  San  Diego  and  Berkeley  and  is  in  progress  in  this  laborafory. 
Some  of  the  points  attacked  are : 

(1)  Reaction  to  auditory,  tactual,  and  visual  stimulations,  and  to 
changes  of  position  of  the  body :  The  time  required  for  reaction  to 
the  stimuli  of  the  sort-s  mentioned  is  measured,  and  the  individuals 
are  rated  on  their  average  reaction  times  of  each  sol-t,  and  their 
variability.  While  nothing  important  is  to  be  expected  to  result 
directly  from  the  measurement  of  the  simple  reaction  times  to  sound 
light  and  touch,  even  the  negative  finding,  if  it  occurs,  is  important. 

(2)  Discrimination  time:  The  time  required  to  discriminate  accu- 
rately between  different  stimuli  suddenly  presented. 

(3)  Association  reaction  time:  The  time  required  to  reply  to  a 
spoken  word  with  another  word  which  is  related  to  the  stimulus  Avord 
in  a  prescribed  way.  For  example,  nouns  may  be  given  and  the  re- 
actor required  to  respond  in  each  case  with  an  adjective  appropriately 
modifying  the  noun ;  or  verbs  may  be  given  and  the  reactor  required 
to  respond  to  each  with  the  name  of  an  object  appropriate  for  the 
action  indicated  by  the  verb.  In  this  work  the  time  is  measured  and 
the  appropriateness  or  accuracy  of  the  response  is  evaluated  as  well. 

(4)  The  rate  at  which  a  person  can  learn  a  certain  complicated 
muscular  coordination  involving  the  hands  and  feet  in  somewhat  the 
way  required  in  piloting  a  plane. 

(5)  The  sensitivity  to  gradual  changes  in  the  position  of  the  body 
in  horizontal  and  vertical  planes.  Several  important  researches  are 
in  progress  on  points  connected  with  the  analysis  of  the  highly  com- 
plicated psj'cho-phj'sical  mechanism  involved  in  the  maintenance  of 
equilibrium. 

(6)  The  capacity  to  acquire  certain  simple  forms  of  dexterity. 

(7)  The  temporal  and  other  conditions  of  the  appearance  of  the 
signs  of  fatigue. 


310  AIK   SERVICE   MEDICAL. 

There  are  also  in  progress  experiments  on  orientation:  the  ability 
to  find  one's  wnj  about,  and  to  know,  from  moment  to  mo- 
ment and  from  position  to  position  the  direction  and  distances 
of'  important  near  and  far  features  of  the  environment.  This 
may  readily  be  granted  to  be  a  topic  of  the  highest  importance  for 
aviation,  although  the  various  tests  which  are  being  developed  are 
not  yet  in  the  stage  of  application  to  aviators,  by  which  application 
only,  as  indicated  above,  can  the  practical  value  of  the  tests  be  de- 
termined. 

PSYCHOLOGICAL    INVESTIGATIONS     WITH     LOW     OXYGEN     TENSION. 

1.  Judgment. — A  test  of  judgment  has  been  carried  out  under 
supervision  by  enlisted  psychologists.  On  each  of  a  large  number  of 
blank  playing  cards,  a  nonsense  syllable  was  printed  in  large  letters: 
PEL,  GUJ,  KIM,  CEZ,  etc.  A  card  rack  with  five  compartments 
(fig,  4)  was  made,  into  which  stacks  of  the  cards  fitted  conveniently. 
In  the  second  compartment  from  the  right,  the  shuffled  cards  were 
stacked,  separated  into  groups  of  1?>  by  blank  cards.  Over  the  three 
compartments  at  the  left,  the  following  labels  were  pasted : 


The  reactor  was  required  to  take  the  cards  from  the  stack  one  at 
a  time  and  file  each  card  in  the  compartment  under  the  label  to 
which  the  syllable  on  the  card  had  the  greatest  resemblance.  For 
example,  PEL  belongs  in  the  first  compartment,  having  two  let- 
ters in  common  with  the  first  label,  only  one  in  common  Avitli  the 
third,  and  none  in  common  with  the  second  label.  Cards  which  be- 
longed in  none  of  the  three  compartments  were  to  be  filed  in  the 
compartment  at  the  extreme  right. 

The  psychologist  took  with  a  stop-watch  the  time  for  the  sort- 
ing of  each  set  of  13  cards,  and  signaled  to  the  reactor  to  begin  a 
new  set  every  two  minutes  from  the  beginning  of  the  test.  By  using 
a  fixed  "  headway  ''  in  this  way,  the  amount  of  work  done  is  uni- 
formly distributed  through  the  series. 

At  the  end  of  the  series,  the  filed  cards  were  checked  for  errors. 
Normal  and  rebreathing  series  Avere  taken  on  12  reactors.  In  the 
"  normal "  series,  the  reactor  sat  before  the  rebreathing  machine, 
with  the  mouthj)iece  and  nose  clip  in  place,  but  breathing  normal  air. 
The  tyj)ical  results  in  one  subject,  showing  the  practice  effect,  and 


AIR    SKRVIOE    MEDICAL.  311 

lack  of   consistent  oxygen   effect    up   to   the   beginning   of   general 
psychomotor  decline  are  presented  in  figure  5. 

2.  Tactual  discrimination. — A  test  of  tactual  discrimination  was 
carried  out  under  supervision  in  the  following  wa}':  Cards  were 
prepared,  each  having  a  diamond-shaped  hole  cut  in  it  in  one  of 
four  positions  (fig.  (>).  The  card  rack  as  described  in  the  pre- 
ceding experiment  was  used  with  a  scree^  so  arranged  that  the 
reactor  could  not  see  the  cards  nor  his  hands.  Above  each  of  four 
of  the  compartments  of  the  rack  was  fixed  one  of  the  four  types  of 
cards  and  in  view  of  the  reactor.  The  cards  to  be  sorted  were 
shuffled,  arranged  in  sets  of  20,  separated  by  blank  cards  in  the  fifth 
(right-hand)  compartment. 

The  reactor  was  required  to  take  the  cards  off  the  stack,  one  at  a 
time,  identif}'  them  by  feeling  them  with  the  fingers,  and  file  them 
in  the  proper  compartments.  Time  was  taken  on  the  sets,  and  subse- 
quent check  of  the  sorted  cards  made  for  errors,  as  in  the  judgment 
experiment.  "  Normal "  series  on  10  men  Avere  conducted  with  the 
mouthpiece  and  nose  clip  of  the  rebreathing  apparatus  in  place, 
but  with  the  reactor  breathing  normal  air,  and  other  series  taken  on 
the  same  men  while  rebreathing.  In  this  test  no  "headway"  was 
used,  the  reactor  commencing  on  another  series  as  soon  as  one  was 
Hnished.  A  typical  result  of  the  normal  and  rebreathing  series  on 
one  man  is  presented  in  figure  7. 

8.  Code  test. — A  code  test  gave  results  similar  to  the  foregoing 
tests,  except  that  in  the  reading  of  the  material  to  be  coded  adjust- 
ments of  accommodations  and  convergence  are  important,  and  dete- 
rioration in  these  functions  in  some  cases  seriouslj?-  affected  the 
results. 

8-B 

A  B  C  D  E  F  G  fl  T  J  Iv  T.  M  N  O  l>  Q  R  S  T  TT  \MV  X  Y  Z 
H  U  M  C  B  T.  Y  E  S  I  r>  K  N  A  X  W  P  T  V  Q  R  O  .7  a  Z  F 

K  X  B  K  P  G  S  I     Z  R  Y  U  I.  K     E  H  Q  X  E  G  li  D  W  V 

O  I     X  W  T  B  A  Y  K  E  B  D  E  (}  K  G 

Fig.  8. — Code  test. 

In  this  test,  the  codes' used,  and  the  material  to  be  coded,  were  aj- 
ranged  on  a  series  of  cards  as  in  figure  8,  and  these  cards  were  pre- 
sented in  succession  to  the  reactor,  who  was  required  to  write  the 
coded  message  in  the  lower  part  of  the  card. 

4.  Dynamometer  test. — In  order  to  find  the  effect  of  asphyxia- 
tion on  the  muscular  force  capable  of  exertion  by  limited  systems,  a 
series  of  dynamometer  tests  were  run  through.  In  these  tests,  the 
reactor  was  required  to  exert  his  maximal  effort  on  a  hand  dyna- 


312  AIR  SEBVIOE  MEDICAL. 

mometer  every  two  minutes.  Normal  and  rebieathing  series  were 
taken  on  10  reactors.  Typical  results  on  one  reactor  are  presented 
in  figure  9. 

5.  Handwriting. — In  order  to  measure  the  effect  of  oxygen  hun- 
ger at  different  barometric  pressures,  and  the  completeness  of  the 
restoration  process  attained  by  the  administration  of  oxygen,  a  sim- 
ple handwriting  test  was  devised  and  carried  out  in  the  low-pressiire 
chamber.  A  standard  psychological  vocabulary  test  of  100  words 
was  used  in  making  up  the  test  cards.  The  100  words  of  the 
standard  vocabulary  test  were  cut  up  and  put  in  a  hat  and  shuffled. 
As  the  words  were  drawn  from  the  hat  they  were  typewritten  on 
a  standard  library  card.  By  this  method  three  test  cards  of  100 
words  each  were  obtained.  The  task  of  copying  these  cards  offered 
the  same  difficulty  to  the  subject  since  the  same  words  were  used  on 
each  test  card  only  the  order  being  different.  Since  the  copying 
of  words  is  an  old-established  habit,  there  was  little  improvement 
through  practice. 

The  test  was  carried  out  as  follows : 

The  subject  was  seated  at  a  table  in  the  tank.  On  a  given  signal 
the  motor  of  the  tank  was  started,  but  the  pressure  was  not  changed. 
The  subject  was  handed  card  No.  1  and  was  asked  to  copy  it  as 
neatly,  as  rapidly,  and  as  accurately  as  he  could.  As  soon  as  this 
task  was  completed,  the  time  of  writing  the  card  was  taken.  (This 
gives  the  normal  record.)  The  signal  for  ascent  (decrease  in  pres- 
sure) was  then  given.  The  ascent  was  made  at  the  rate  of  about  1,000 
feet  per  minute.  After  the  subject  had  reached  the  given  height 
he  was  kept  at  that  level  for  15  minutes  with  the  motor  running  (to 
keep  the  noise  constant).  At  the  end  of  the  15-minute  period  at 
the  given  height  the  subject  was  asked  to  copy  the  second  test  card. 
After  completing  the  copying,  his  time  was  taken  as  before.  (This 
gives  the  oxygen-hunger  record.)  The  subject  was  then  given  oxy- 
gen for  two  minutes  and  was  then  asked  to  copy  the  third  test  card. 
(This  gives  the  oxygen-restoration  record.)  Upon  the  completion 
of  the  latter,  the  signal  for  descent  was  given. 

The  results  from  these  handwriting  tests  were  then  treated  as 
follows:  First,  they  were  measured  (with  reference  to  general  form 
and  legibility)  on  the  scale  for  handwriting.  This  scale,  as  is  well 
known,  enables  one  directly  to  measure  the  quality  of  a  given  hand- 
writing production  in  terms  of  certain  units.  For  example,*  his 
normal  might  correspond  to  unit  12  on  the  scale;  his  oxygen-hunger 
record  might  correspond  to  unit  8  on  the  scale. 

In  rating  the  tests  on  the  various  subjects  a  penalty  of  20  was 
attached  for  each  unit  lost  on  the  scale.  In  addition  to  this  rating 
on  the  scale,  the  following  penalties  were  also  imposed : 


CAPT.   BORING.      (Fig.    10a.) 
Handwritinfr.  standard  card — normal.     14.000  ft. 


iJ^^y    1^>..^^L.     :^.H^^_^      CtC^vl^      OX^.4^,.     }4., 


CAPT.   BORING.      (Fig.    10b.) 
Handwriting,  standard  card — oxygen  hunger.     14,000  ft. 


2*<.'>^'^C      Xa  M-\-     ff\-«-*J— ^~J     i-«-c..   (^>iiw^ 


■  ■  •  r-."Sj^;. -..•_. 


_j : 1 LLJi 


CAPT.   BORING.      (Fig.    10c.) 
Handwriting,  standard  card — oxygen  restoration.     14.000  ft. 


3-1 


PVT.  WICKMAN.      (Fig.   11a.) 
Handwriting,  standard  card — normal.      18,000  ft. 


PVT.   WICKMAN.      (Pig.   lib.) 
Handwriting,  standard  card — oxygen  hunger.     18,000  ft 


-  f.  c-i^---               •  .i-^^^^.,fA^  yX<^-^<''^Oy^,         -^J'Xi.'--^^;-'     ■^■-u.^^-Jt-^ 

■-/-,./,, 

'   1  /u 

•--tc,  t'   t 

<  i^^'jj 

i-'  ■  o 

,^      ,^       .    </,■                    ■■     •                                  '    '^~.<-           Lt(,,U^y^i^^ 

.  y      . 

.  ^-,ii--".(ri  "Tt^Sx-laM   ■^-^<^-^<'  •'n-^         ''-ULft/c^vf.v.-/^^-, 

,  -    .' 

.£    v-'Y     ^-^«^^-    :jv^-v'    ,i<.i-'>'''-t-L«_.-  >^f  f-^ffi-     '..,c 

■     ■'.:  -••-'■ 

....      ......              ^ 

PVT    WICKMAN.      (Fig.    lie.) 
Handwriting,  standard  card — oxygon  restoration.      18.000  ft. 


W^     .'    t^Tj^^ 


183-2 


CAPT.    DAVIS.       (Fig.    lL>a.) 
Handwriting,  standard  card — normal.  L'2,000  ft. 


■I  J_ 


<^i-<Ut«V.< 


'<»<. 


CAPT.    DAVIS.       (Fis.    12b.) 
Handwritins'.  standard  card — und<?r  oxygen  banger.      22.000  ft. 


-3x"'  -  - 

*-i 

J 

i-{ 

.■>-V"    >a 

-  'a 

.-.• 

1    _v.l.,'.-. 

.\<jC-f.^'^-  _ 

^•i^  >'<.-^ct^ 

■    *-■     mJ~^ 

.'JLj^^  v''i  <  u<. 

v.:  t  -  • 

6 

i.o.-. 

"  1.  <L  <^  (»,v.^  ._ 

CAPT.   DAVIS.      (Fig.   12c.) 
Handwriting,    standard    card — oxygen    restoration.      22,000    ft. 


19^5   > 


183-3 


Am  SERVICE   MEDICAL. 


313 


For  each  word  omitted,  a  penalty  of  2. 

For  each  word  misspelled  or  wrong  word  used,  a  penalty  of  2. 

For  each  word  crossed  out  and  rewritten,  a  penalty  of  2. 

For  each  word  careted  in,  a  penalty  of  2. 

For  each  word  or  letter  thereof  written  over,  a  penalty  of  2 

each  word. 
Failure  to  follow  line  as  well  as  original,  a  penalty  of  2. 
For  each  10  seconds'  increase  in  time  over  the  normal,  a  pen- 
alty of  1. 
For  each  10  seconds'  decrease  in  the  time  of  writing,  a  credit 
of  1  was  given. 
It  will  thus  be  seen  that  errors  in  the  normal  are  estimated  as  well 
as  those  made  under  oxygen  hunger  or  after  oxygen  administration. 
A  typical  record  follows: 

Record  of  Pvt.  WicJcman,  altitude  18,000  feet. 


Normal. 


Under 
oxygen 
hunger. 


Two 
minutes 
after  ad- 
ministra- 
tion of 
oxygen. 


Legibility  rated  on  scale,  last  8  lines  only  (penalty  of  20  for  each  imit  lost 
on  scale;  credit  of  20  for  each  unit  gained) 

Word  omitted  (penalty  of  2  each  word) 

Word  mispelled  or  wrong  word  used  (penalty  of  2  each  word) 

Word  scratched  out  and  rewritten  (penalty  of  2  each  word) 

Word  careted  in  (penalty  of  2  each  word) 

Word  (or  anv  part  thereof  written  over,  penalty  of  2  each  word) 

Failure  to  follow  line  as  well  as  original  (penalty  of  2  each  line  on  last  8 
lines) 

Time,  penalize  1  for  each  10  seconds  increase  or  credit  1  for  each  10  seconds 
decrease 

Total  penalties  or  credits 


80 
12 


0 
n 

0 
0 

0 

0 

0 

+  3 


-  6 


-  100 


-I-  3 


These  tests  have  been  made  at  14,000  feet,  16,000  feet,  18,000  feet, 
and  22,000  feet.  While  complete  records  are  not  in,  the  results  so 
far  obtained  show  that  at  14,000  feet  the  effect  of  oxygen  hunger  is 
exceedingly  slight  (see  fig.  10)  ;  at  16,000  feet  the  effect  is  scarcely 
more  noticeable;  while  at  18,000  feet,  on  some  subjects,  at  least, 
the  effect  is  extremely  marked  (see  fig.  11,  the  same  subject).  The 
handwriting — in  some  cases — becomes  difficult  to  read,  whereas  other 
errors  in  spacing,  following  the  line,  omission  of  words,  etc.,  are 
A^ery  marked.  At  22,000  feet  the  first  two  subjects  fainted,  and  it 
Avas  not  possible  to  continue  the  experiment.    So  far  only  one  record 

has  been  obtained  at  22,000  feet  (fig.  12).^ 

In  every  case,  except  those  where  heart  dilatation  and  fainting 
occurred,  the  2  minutes'  administration  of  oxygen  completely  re- 
stored the  handwriting  to  normal. 

^  It  should  be  noted  that  the  altitudes  are  given  by  altimeter  readings,  and  should  be 
considerably  increased  if  allowance  is  made  for  the  difference  in  temperature  of  the  air 
in  the  tank   and  that   corresponding  to   the  same  pressures   in  the  upper   atmosphere. 


314  Am  kSTirvick  mkdtcal. 

It  was  planned  to  continue  this  experiment  by  the  same  method 
with  the  machine-gun  camera  and  with  a  telegraph  recording  outfit , 
and  to  obtain  and  contrast  a  similar  set  of  records  on  the  rebreath- 
ing  tank  and  the  refrigerated  pressure  chamber.  It  was  thought 
that  the  results  on  the  handwriting  test,  the  machine-gun  camera, 
and  the  recording  telegraph  would  give  a  tangible  picture  to  the 
aviator  of  just  what  difficulties  he  would  meet  with  in  the  air  in 
writing  messages,  in  sending  them,  and  in  the  accuracy  of  his  ma- 
chine-gun work,  and  how  these  difficulties  could  be  overcome  by  the 
use  of  oxygen. 

6.  Mem,or-y. — Various  tests  on  memory  were  employed.  For  im- 
mediate memory,  series  of  from  5  to  12  consonants  are  numbered, 
and  series  of  from  2  to  5  observations,  each  made  up  of  a  color  name 
and  a  number,  were  employed.  Samples  of  the  consonant  series  and 
observation  series  are  given  below : 

RKZWT 

CXWNZF 

.TLXBRVN 

NHBDZVCR 

VJSRBLTMW 

HRKGWMDPTL 

ZXWKDTNVSHQ 

YPCQDKWZMTB.T 

The  observation  series  were  made  up  in  pairs  of  series,  the  same 
color  name  not  occurring  in  both  series,  and  in  the  tests  the  two 
members  of  a  pair  were  given  in  succession,  in  order  to  avoid 
confusion  between  successive  series. 

The  "  observation  tests  "  were  especially  satisfactory  as  tests  and 
may  be  used  successfully  where  immediate  memory  tests  are  required. 
Neither  test,  however,  showed  any  deterioration  in  immediate  mem- 
ory due  to  asphyxiation. 


a. 

b 

white 

..  63 

ecru 

..  81 

russet 

..  84 

black 

5',^ 

gray 

-.  47 

{,Teen 

..  24 

amber 

..  28 

lilac 

..  1?> 

violet 

..  96 

orange 

..  35 

red 

..  58 

blue 

..   7t 

tan 

..  14 

buff 

..  29 

gold 

..  85 

rose 

..   95 

azure 

..  46 

drab 

..   02 

yellow 

..  69 

purple 

..   79 

scarlet 

..  57 

crimson 

..   13 

straw 

..  25 

slate 

..   68 

brown 

..  18 

pink 

..  37 

lavender.... 

..  36 

indigo 

..  92 

AFR    SERVTOE    MEDICAL.  316 

Foi-  visual  memory  the  position  memory  board  (fig.  B)  was  used. 
This  board  has  mounted  in  a  vertical  plane  49  miniature  lamps 
ai-ranged  in  a  square  pattern,  the  individual  lamps  3  inches  apart, 
vertically  and  horizontally.  By  means  of  a  plug  board  and  master 
key  behind  the  board  any  number  of  lights  from  1  to  14  can.be 
lighted  simultaneously  in  any  chosen  position.  In  practice  the 
reactor  was  shown  from  three  to  seven  lights  for  three  seconds,  and 
then  required  to  chart  the  positions  on  a  printed  form  (fig.  14). 
The  lights  were  presented  before  or  during  the  rebreathing  test,  and 
the  charting  was  done  immediately,  or  after  a  short  or  long  interval. 
While  no  effects  of  asphyxiation  were  demonstrable  up  to  the  time 
at  which  the  marking  of  the  chart  became  impossible  on  account  of 
disturbance  of  motor  control,  the  method  appears  valuable  for  other 
than  the  rating  work. 

7.  Mathew^tical  tests. — Several  mathematical  tests  were  employed, 
the  most  satisfactory  being  the  attention  test.  In  this  test  two 
sheets,  each  containing  16  lines  of  45  digits  each,  were  used.  Each 
of  the  32  lines  of  digits  was  carefully  made  up  so  that  the  lines 
two  sheets,  each  containing  16  lines  of  4o  digits  each,  were  used. 
Each  of  the  32  lines  of  digits  w^as  carefully  made  up  so  that  the  lines 
presented  equal  difficulty.  Before  commencing  the  test  a  standard 
number  of  12,  13.  14.  or  15  was  written  before  each  line  and  the 
reactor  required  to  add  the  digits  in  each  line,  beginning  at  the  left, 
until  the  progressing  sum  equaled  the  standard  number  or  one  over- 
that  number,  drawing  in  each  case  a  line  between  the  last  digit  of  the 
group  added  and  the  next  digit  and  writing  the  difference,  if  any, 
between  the  stun  of  the  group  and  the  standard  number  over  the 
group.  By  changing  the  oi-der  of  the  standard  number,  128  lines  are 
available.    A  typical  sheet  of  this  test  is  shown  in  figure  15. 

This  test  showed  no  definite  asphyxiation  effects  prior  to  the*period 
of  general  psychomotor  decline,  and  is  affected  somewhat  by  eye  con- 
ditions and  practice  effects.  It  has  shown  possibilities  of  advan- 
tageous use  for  other  practical  purposes,  however,  and  work  will  be 
continued  with  it. 

8.  Auditory  tests. — Tests  on  the  sensitivity  and  acuity  of  the  vari- 
ous sense  organs.  By  using  brief  tests  which  permit  the  attainment 
of  "  attention  peaks."  it  is  demonstrable  that  the  efficiency  of  the 
vai'ious  sensory  mechanisms  does  not  show  appreciable  deterioration 
until  the  general  psychophysical  breakdown.  Our  detailed  work  has 
been  principally  on  auditory  efficiency,  with  some  work  on  visual 
efficiency  done  before  the  ophthalmological  section  was  organized. 

Tests  on  the  range  of  auditory  perception  of  12  reactors,  with  a  set 
of  22  steel  cylinders,  with  range  up  to  32,000  vibrations  (fig.  16), 
showed  no  difference  between  normal  and  rebreathing  series  up 
to  the  point  of  general  psychomotor  inefficiency.     Tests  with  the 


316  ATB  SEBVIOE  MEDICAL. 

acumeter  (fig.  IT)  for  sensitivity  to  the  note  of  256  vibrations  are 
at  present  being  carried  on,  and  so  far  indicate  no  consistent  deteriora- 
tion of  sensitivity  until  the  late  stages  of  asphyxiation.  In  other 
words,  the  reactor  can  hear  as  faint  a  sound,  up  to  a  late  stage  of 
asphyxiation,  as  he  can  in  normal  condition  if  his  attention  is  good 
at  the  moment  of  listening.  As  has  been  previously  explained,  the 
"  attention  peaks  '"  can  be  evoked  even  in  relatively  late  stages  of 
asphyxiation  if  the  experiment  is  conducted  by  the  methods  usually 
employed  by  trained  psychologists. 

9.  Continuous  reaction. — The  continuous-reaction  board  (fig.  18) 
which  was  used  in  one  of  our  early  tests,  and  which  was,  as  a  matter 
of  fact,  the  starting  point  from  which  our  final  apparatus  for  the 
rating  tests  (LVN  apparatus)  was  developed,  could  not  be  used  for 
rating  work  because  of  the  rapid  but  variable  improvement  with 
practice  in  its  manipulation.  In  this  apparatus  21  miniature  lights 
are  arranged  in  a  circle,  with  a  two-way  switch  at  the  base  of  each. 
By  a  master  switch,  a  lamp  is  lighted ;  the  reactor  is  required  to  turn 
off  each  lamp  as  soon  as  it  lights  by  moving  the  appropriate  switch ; 
the  turning  off  of  one  lamp  turns  on  another  at  some  point  in  the 
semicircle  determined  by  the  previously  arranged  interconnection  of 
a  switchboard  concealed  within  the  apparatus  so  that  the  reaction  is  a 
continuous  one  until  the  twenty-fourth  lamp  has  been  turned  out,  or 
may  be  continued  through  a  longer  period. 

IV.  FURTHER  PSrCHOLOGICAL  INVESTIGATIONS  OF  PROBLEMS  OF  AVIATION. 

1.  Decrease  of  after-nystagmus  ti/mes  with  successive  rotations. — 
The  importance  assigned,  in  the  examination  of  aviators,  to  certain 
ocular  movements  which  follow  upon  rotatory  movements  of  the  head 
and  body  has  suggested  an  experimental  investigation  into  the  effect 
upon  these  ocular  movements  of  rotations  continued  for  several  days 
or  weeks  together.  Experiments  have  made  it  apparent  that  under 
certain  circumstances  persistent  rotation  in  the  clinical  revolving 
chair  leads  to  a  considerable  reduction  in  the  violence  and  the  dura- 
tion of  these  characteristic  ocular  movements.  In  one  case  the  dura- 
tion of  the  after-nystagmus,  e.  g.,  as  observed  during  May,  1918,  fell 
from  about  25  seconds  to  11  seconds  after  several  daily  series  lasting 
for  a  few  minutes  a  day  at  a  constant  rate  of  one  revolution  in  2 
seconds. 

Further  to  investigate  the  effect  of  repetition  upon  ocular  move- 
ments, six  enlisted  men  were  turned  ten  times  a  day  (five  times  right 
and  five  times  left)  between  June  6  and  July  13,  1918.  Two  of  the 
men  were  begun  later  than  the  others  and  intervals  of  one  or  more 
days  interrupted  here  and  there  the  continuity  of  the  diurnal  trials. 
The  results  are  given  in  the  accompanying  Table  I  (fig.  19)  and  chart. 


AIR   SERVICE  MEDICAL. 
Table  I. 


317 


1 
Brown. 

Caplan. 

Rahill. 

Stewart.     Wichmann. 

Ackermann. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V.    Av. 

M.V. 

Av. 

M.V. 

June    6 

R 

26.6 
27.6 
27.2 
27.0 

1.9     23.2 
1. 7     29. 4 

2.6 

2.5 
3.9 
2.8 

22.2 

20.6 
22.8 
20.0 

2.2 
1.5 
2.2 

24.3 

25.6 
22.0 
28.0 

6.7 
1.5 
4.0 
3.0 

L 

1-5 

2.2 
1.6 

27.6 
25.0 

6-10 

7 

R 

L 

1-5 

6-10 

8 

R  .. 

22.3 
2.5.0 
24.0 
16.7 

2.9 
2.0 
4.0 
4.3 

20.8 
20.2 
21.6 
19.4 

1.4 
3.4 
2.3 
2.7 

22.0 
23.6 
19.7 

26.0 

2.6 

3.1 

.9 

1.3 

L 

1-5 

6-10 

9 

R 

L 



1-5 

6-10 

10 

R 

20.2 
21.4 
21.0 
20.6 

.6 

1.3 

1.6 

.5 

19.6 
23. 0 
22.2 
20.2 

14.5 
20.0 
17.5 
16.5 

17.0 
20. 7 
18.3 
17.5 

1.9 
1.2 
2.0 
2.2 

1.3 
1.3 
2.5 
2.5 

2.0 
l.S 
2.8 
2.3 

20.2 
19.0 
20.6 
18.6 

15.0 
1.3.4 
17.0 
11.2 

1.5.8 
13.8 
16.0 
13.6 

12.8 
11.4 
13.6 
10.6 

12.4 
11.0 
13.2 
10.2 

10.8 

10.6 

11.6 

9.8 

3.4 

3.6 
2.9 
3.4 

2.4 
3.0 
2.8 
1.4 

1.4 
2.2 
1.2 
2.1 

1.7 
2.3 
1.9 
1.7 

1.5 

1.2 

.7 

.6 

1.0 

1.5 

1.3 

.6 

L 

1-5 

6-10 

11 

R 

17.6 
17.0 
19.2 
15.4 

16.4 
16.0 
17.0 
15.4 

14.0 
14.4 
16.6 
11.8 

9.6 

9.2 

10.8 

8.0 

6.8 
7.8 
6.6 
8.0 

2.1 
2.4 
1.4 
1.7 

1.9 
1.6 
1.8 
1.5 

4.0 
1.5 
2.1 
1.8 

1.7 

1.7 

.6 

.8 

1.0 
.9 
.9 
.8 

L 

1-5 

6-in 

12 

K 

22.0 
22.8 
21.4 
23.4 

2.8 
2.2 
2.9 
1.9 

28.0 
28.0 
32.2 
23.8 

28.6 
29.4 
31.8 
26.2 

23.4 
24.6 
25.4 
22.6 

5.2 
4.0 
5.6 
2.6 

2.1 
4.7 
2.2 
3.0 

2.0 

1.3 

.7 

1.3 

L 

1-5 

6-10 

13 

R 

L 

1-5 

6-10 

14 

R 

18.0 
16.8 
18.6 
16.2 

1.6 
1.4 
1.1 
1.4 

14.2 
19.2 
17.0 
16.4 

14.2 
15.0 
15.2 
14.0 

.6 

1.8 
2.8 
2.5 

2.6 
2.0 
3.0 
1.6 

L 

1-5 

6-10 

15 

R 

L 

1-5 

...... 

6-10 

16 

R 

I> 

1-5 

6-10 

..."■.. 

17 

R 

L 

24.4 
21.8 
22.6 
23.6 

2.7 
3.4 
2.5 

4.5 

13.0 
18.0 
16.0 
15.0 

14.4 
16.2 
15.6 
15.0 

14.8 
15.2 
16.4 
13.6 

11.4 
11.4 
12.0 
10.8 

9.4 
11.2 
10.2 
10.4 

3.0 

1.0 

.0 

5.0 

1.5 

1.6 
1.1 
2.0 

2.6 
1.4 
1.7 
2.5 

1.1 
.9 
.8 
.6 

.7 
1.0 
1.0 
1.3 

8.8 

9.8 

10.8 

7.8 

10.8 
10.0 
12.0 

8.8 

7.6 
7.8 
8.2 
7.2 

5.6 

5.0 

1 

1.8  1  27.6 
1.5  1  29.0 
1.0  I  27.4 
1.  4      29. 2 

2.7 
1.6 
2.1 
2.2 

2.2 

1.8 

2.1 

.7 

1.9 
2.5 
2.5 
1.9 

2.0 
1.4 
1.3 
2.5 

1.4 
2.6 
2.4 
2.4 

1-5   

6-10 

IS 

R 

14.2 
12.8 
14.0 
13.0 

14.8 
13.4 
15.2 
13.0 

13.4 
11.0 
14.0 
10.4 

7.2 
7.8 
7.6 
7.4 

2.6 
2.4 

2.8 
2.4 

2.2 
.9 

1.8 
.4 

1.8 
2.0 

2.1 

2.0 

2.0 

.7 

.5 

1.4 

.6 

.6 

1.5 

1.2 

.9 

.0 

1.9 

1.6 

1.0 

.0 

23.2 

22.8 
24.6 
21.4 

23.6 
23.6 
23.6 
23.6 

19.0 

22.2 
21.6 
19.6 

15.8 
17.2 
17.0 
18.0 

L 

1-5   

6-10 

19 

K 

18.4 
16.2 
18.0 
16.0 

2.1 
1.4 
1.9 
1.2 

L 

1-5 

6-10 

20 

R 

L 

1-5 

1.6  !     fi.fi 

6-10 

1.3 

.6 
.6 
.9 
.5 

4.0 

1.6 

1.0 

2.6 

.0 

21 

R 

L 

1-5 

6-10 

15.2 
13.4 
14.6 
14.0 

1.0 

.5 

1.3 

.8 

318 


Am  SERVICE   MEDICAL. 
Table  I — Continued. 


BrowTi.         Caplan. 

1 

Rahill. 

Stewart. 

Wichmann.  Ackermann. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V. 

Av. 

M.V. 

Tune  22 

R 

10.0 
10.8 
10.2 
10.6 

.8 
1.7 

.7 
1.8 

5.4 
2.2 

4.8 
.2.8 

.9 
1.7 
1.4 
1.1 

17.0 
18.8 
18.8 
17.0 

2.4 
2.2 
1.9 
2.4 

L 

1-5 

6-10 

23 

R 

L 

1-5 

6-10 



24 

R 

L 

1-5 

6-10 

R 

11.6       1.5 
11.2  1     1.0 
11.8       1.0 
11.0       1.2 

7.0 
8.4 
8.0 
7.4 

7.8 
8.2 

8.4 
7.8 

6.6 

8.6 
8.2 
7.0 

1.2 

1.5 

.8 

2.4 

1.0 
1.0 
1.1 
1.2 

1.3 
2.5 
2.2 
2.0 

7.6 
7.2 
8.6 
6.2 

7.6 
6.6 
2.3 
1.7 

8.6 
6.8 
7.4 
8.0 

2.1 
1.8 
1.4 
1.8 

2.3 
1.7 
1.5 
1.7 

.5 
1.0 
1.1 

.8 

1.4 

.6 

1.2 

.8 

.0 
.0 
.0 
.0 

.0 
.0 
.0 
.0 

1.4 
.9 
.8 
.5 

.0 
.0 
.0 
.0 

.0 
.0 
.0 

.0 

15.0 
16.0 
16.4 
14.6 

12.8 
14.2 
15.4 
11.6 

10.4 
10.8 
11.4 

9.8 



2.0 
2.4 
1.3 
2.3 

2.2 
1.8 
1.9 
1.3 

1.7 
1.4 
1.5 

2.2 

25 

L 

1-5 

*  *  * ' 

6-10 

26 

R 

10.8 
9.4 

10.8 
9.4 

1.4 
.5 

1.4 
.7 

L 

1-5 

6-10 

27 

R 

29.4 
31.2 
31.4 
29.2 

23.4 
29.8 
25.2 
26.0 

21.6 
22.6 
20.6 
16.6 

2.3 

L 

2.fi 

1-5 

' 

2.3 

6-10 

3.0 

28 

R 



1.3 

L 

• 

I  0 

1-5 

1 

l.S 

6-10 

.1 

2.4 

29 

R 

1 
1 

1.1 

L 

1 

2.1 

1-5 

............ 



3.3 

6-10 



1 

1.9 

30 

R 



L 

1-5 

6-10 

Jnlv      1 

R 

14.8 
14.4 
13.0 
16.2 

15.4 
14.8 
15.2 
15.0 

13.4 
13.8 
14.2 
13.0 

1.8 
1.7 
1.2 
1.0 

.5 
.7 
.3 

10.4 
7.4 
7.6 

10.2 

6.0 
6.0 
6.8 
5.2 

1.9 
2.5 
2.5 
1.4 

1.6 

.8 

1.0 

1.4 

20.8 
23.4 
24.0 
20.2 

17.8 
18.4 
17.4 
18.0 

14.2 
13.6 
14.2 
13.6 

1.4 

2.9 
2  4 
1.0 

3.6 
1.1 
2.1 
2.2 

3.4 
1.9 
3.8 
1.5 

18.2 
19.0 
20.6 
16.6 

14.2 
16.8 
16.4 
14.6 

15.8 
15.2 
16.2 
14.8 

2  6 

L 

3  2 

1-5 



3  3 

6-10 

1  9 

2 

R 

1  9 

L 

1-5 

1.4 

2  7 

fr-lO 

£•;.;:::::::::::: 

1-5 

6-10 

R 

.1 

\:l 

1.0 
1.6 

1.3 

3 



l.S 

1.2 

1.4 

1.4 

4 

L 

1-5 

. 

6-10 



5 

R 

8.4 
6.8 
8.8 
6.4 

8.4 
6.2 
8.2 
6.4 

1.3 
1.0 
1.0 

.9 

.7 
1.0 

.6 
1.3 

17.4 
15.2 
15.4 
17.2 

13.0 
14.2 
14.0 
13.2 

2.3 
2.2 
2.6 
2.2 

1.6 

.3 

1.2 

1.0 

13.2 
14.4 
13.8 
13.8 

12.0 
14.6 
13.0 
13.6 

1  4 

L 

9 

1-5 

1  0 

6-10 

1  4 

0 

R 

1  2 

L , 

:::;::::" 

.=i 

1-5 : 

1  2 

6-10 

1  4 

7 

R 

i 

L 

1-5           

«-I0 

AIR   SERVICE    MEDICAL. 


319 


Table  I — Continued. 


Brown. 

Caplan.  '       RahiU. 

Stewart. 

Wiehmann.  Ackermann. 

Av. 

M.V. 

Av.    M.V.    Av. 

M.V. 

Av.  ' 

M.V. 

Av. 

M.V. 

1 
Av.  ;  M.V. 

JuJy    8 

R 

L 

1-5 

6-10 

L 

1-5         

18.0 
16.4 
15.8 
18.6 

13.4 
11.6 
14. 6 
10.4 

2.0 
1.9 
1.8 
1.5 

1.9 

1.9 

.9 

.9 

12.6 

10.6 

13.4 

9  8 

10.6 
9  4 

10.2 
8.8 

1.3 

1.9 

.5 

1.0' 

1.3 
.9 

1.1 
.6 

18.4 
17.0 
17.4 
18.0 

11.8 
10.6 
12.0 
10.6 

2.1 

.4 
1.8 
4.0 

1.8 
1.4 
1.6 
1.5 

12  2         2  2 

......J 

] 

12  2         10 

12. 2  1      2. 2 
12  2         10 

9 

10.8         1.4 
12.4         1.1 
12. 6            9 



6-10 

R 

1 

10  6         13 

9 

1 

8  2         1  " 

I,                     

8.2 
8.8 
7.6 

11.0 

9.8 

10.0 

10.8 

9.6 
8.4 
9.6 
8  4 

1.0 

1.0 

.7 

4 

1-5             

6-10 

10 

R       

9.2 

9.8 

8.4 

10.6 

1.8 
2.6 
1.7 
2.3 

L              

1.0 

.8 

1.0 

1  3 

1-5           

f>-10           

" 

u 

R 

9.6 

9.0 

10.0 

8.6 

8.6 
8.2 

8  8 

.9 

.4 
.4 
.  5 

.8 
.3 
.6 
.4 

.3 
.6 
.6 
.3 

L 

1  1 

1-5         

9 

(i-10       

1  t 

i2 

R 

9.2           .5 
9.0            "< 

L 

1-5           

9.4 
8.8 

7.6 
6.8 
7.8 

6  6 

.4 

6-10 

8.0 

13 

R          

7.2 
6.8 
7.2 
6.S 

1  5 

L 





(^ 

1-5 

1.3 

o 

t;-10           



14 

R 



L 

1-5 

6-10 



15 

R 

i 

6.4 
6.6 
6.6 
6.4 

5 

L 

1 

7 

1-5 

1 

'  ^ 

6-10 

5 

16 

R 



L 

1-5 

0-10 

17 

R 





7.6 
7.2 
7.6 
7.2 

5 

L 

1 

3 

1-5 

5 

6-10 

1 

1 

•1 

18 

R 

; 

1 

i 

.  u 

L 



1 

1 

1-5 

' 

6-10 

i 

1 

1 

1 

TLe  method  of  observation  and  record^  was  improved  (1)  by  timing 
the  rotatory  movement  of  the  chair  with  the  sound  of  a  seconds'  met- 

1  In  adopting  a  definite  standard  technique  for  the  conduct  of  a  large  number  of  ex- 
aminations to  l:»e  held  at  scattered  stations  by  many  examiners  under  varying  conditions, 
the  use  of  complicated  instruments  of  precision  is,  of  course,  neither  necessary  nor 
practicable.  Intervals  of  a  day  or  more  betwt'en  turnings  were  sometimes  inevitable  owing 
to  the  military  duties  of  the  men  examined.  It  will  be  noted  that  there  occurs  quite  a 
variation  in  the  readings  from  day  to  day.  This  may  be  due  to  slight  variation  in  the 
stimulation  employed  or  to  inaccuracies  in  reading  the  nystagmus.  The  former  factor 
was  overcome  as  far  as  possible  by  timing  the  rate  of  turning  with  a  stopwatch,  while 
the  latter  was  minimized  by  having  all  the  readings  taken  by  one  observer.  These 
variations,  however,  do  not  vitiate  the  main  results  as  stated  above. 


320  AIR   SERVICE   MEDICAL. 

ronome  used  to  replace  ji  stop  watch  and  (2)  by  recording  the  later 
phases  of  nystagmus  upon  a  revolving  drum  with  time  marker, 
Jacquet  seconds  clock,  and  telegrapher's  key.  The  auditory-kinaes- 
thetic  rhythm  incited  by  the  metronome  forms  a  much  more  natural 
and  accurate  control  for  the  rotation  of  the  chair  than  the  stop  watch, 
and  the  graphic  record  of  eye  movements  eliminates  the  double  erroi- 
of  anticipating  and  delaying  the  cessation  of  nystagmus,  an  error 
inherent  in  the  single  movement  of  the  thumb  or  finger  upon  the  stem 
of  the  watch.  This  double  error  may  amount  to  several  seconds.  The 
usual  stop-watch  method  offers  no  means  of  control  over  the  variable 
errors  of  expectation  and  habituation  and  the  constant  errors  of  time. 
All  of  these  errors  are,  of  course,  scrupulously  calculated  in  any  rec- 
ognized method  of  science. 

These  experiments  were  conducted  by  assistants  in  the  laboratory. 
From  time  to  time  the  method  was  inspected,  and  occasional  readings 
were  made  of  after-nystagmus  with  the  stop  watch.  In  the  table  each 
average  time  for  5  right  turns  and  5  left  turns  is  given,  as  well  as 
the  average  of  the  first  .5  and  the  last  .5  turns  in  each  series.  Mean 
variations  are  calculated  in  each  case.  In  every  instance  the  rate  was 
10  turns  in  20  seconds.  Intervals  of  two  minutes  (between  right  and 
left)  and  three  minutes  (between  pairs)  were  observed.  In  a  few 
cases  the  regular  series  was  interrupted  or  shortened  by  severe  organic 
disturbances  revealed  by  nausea,  qualmishness,  pallor,  excessive  respi- 
ration, and  general  distress. 

The  results  bear  evidence  of  the  decline  of  the  duration  of  after- 
nystagmus  (1)  from  day  to  day  and  (2)  from  trial  to  trial  within  a 
single  period  of  experimentation. 

The  average  times  for  the  four  observers  who  began  on  June  6  run 
as  follows  from  day  to  day : 

Seconds.  Seconds. 

June  6 24.9     June  18 13.0 

8 22.3               19 13.  .5 

10 20.6                20 9.6 

11 16.2                21 8.3 

12 18.0               22 7.1 

13 13.6               24 6.8 

14 13. 8               2.5 5. 0 

15 10.8               26 6.3 

17 15.9 

In  20  days,  then,  the  decrease  in  time  exceeds  18  seconds  (24.9—6.3 
seconds).  The  drop  in  time  is  fairly  consistent  in  spite  of  the  fact 
that  it  proved  to  be  impossible  to  arrange,  without  exception,  the 
daily  program.  The  temporal  decline  is  graphically  expressed  in  the 
chart,  which  is  based  upon  the  nystagmus  for  the  first,  fifth,  tenth, 
and  fifteenth  turning  days,  regardless  of  calendar  dates,  for  all  six 


♦  ATE  SEBVTCE   MEDICAL.  321 

subjects.  The  initial  times  for  all  subjects  fell  within  22-31  seconds; 
and  the}'  decline  at  somewhat  unccjnal  intervals  for  the  different  men. 
The  total  range  of  decline  expressed  in  whole  numbers  for  the  first 
10  days  stood  as  follows: 


Subject  A 30—12=18  seconds 

Subject  B 27—10=17  seconds 

Subject  C 26—11=15  seconds 


Subject  R 21—14=  7  seconds 

Subject  S 25—  8=17  seconds 

Subject  W 28—15=13  seconds 


The  difference  is  not  very  gi-eat,  save  in  the  case  of  E,  whose  times 
were  least  shortened  within  this  limited  time.  E  dropped  sharply 
(14  to  8  seconds),  however,  within  the  next  five  days,  while  S  fell 
off  to  zero. 

To  revert  to  the  decrease  in  time  of  the  ocular  movements  during 
the  period  of  experimentation  each  day,  the  times  nearly  always 
decline  during  the  10  trials,  as  in  the  case  of  the  May  experiments 
made  upon  the  single  subject.  The  few  negative  cases  are  significant. 
The  most  striking  case  appears  in  S's  first  two  days.  On  these  two 
days  the  subject  became  so  violently  nauseated  that  the  trials  had  to 
be  broken  off  after  the  sixth  turn.  Thereafter  the  ocular  movements 
grew,  from  day  to  day,  much  less  violent  and  of  smaller  excursion, 
qualmishness  disappeared,  and  the  nj^stagmus  rapidly  lessened  in 
duration.  All  of  the  other  negative  cases  of  more  than  a  second  or 
so  occurred  just  after  two  or  more  blank  days  and  they  fell  in  with 
an  absolute  increase  in  nystagmus  time,  and  usually  with  a  greater 
violence  in  the  general  organic  effects  of  rotation.  These  blank  days 
Avere  coincident  with  holiday  leaves  for  the  subjects  during  which 
their  daily  routine  was  interrupted.  The  disturbance  of  routine  may 
very  well  have  led  to  a  physiological  disturbance  producing  a  cumu- 
lative effect  and  masking  the  usual  decline  during  the  last  half  of  the 
period. 

It  seemed  altogether  probable  that  the  change  of  after-nystagmus, 
which  occurred  not  only  from  turn  to  turn,  but  also  from  day  to  day, 
should  be  a  function  of  elapsed  time  as  well  as  of  repetition.  The 
accompanying  table  (II)  gives  the  relative  frequency  of  increase 
and  decrease  in  after-nystagmus  after  intervals  and  immediately 
after  turning  days.  The  totals  for  all  subjects  suggest  that  the  blank 
days  retard  the  gradual  decline  to  which  attention  has  been  called. 
But  a  scrutiny  of  the  table  will  make  it  apparent  that  virtually  all 
the  positive  evidence  is  confined  to  the  figures  for  the  last  two  sub- 
jects (E.  and  W.),  who  also  reported  an  increased  violence  in  the 
apparent  visual  movements  and  in  organic  disturbances  after  in- 
tervals of  rest. 


322 


AIJR    SERVICE    MEDICAL. 


Table  II. 


1 

i       After  interval. 

1 

After  no  inten'al. 

Increases. 

Decreases. 

Increases. 

Decrea.ses. 

Ackerman 

B  rowD     

1 

8 

5 
12 

7 
6 
5 
2 

3 

? 

4 

ti 

IC 
4 

Caplan 

Stewart 

Rahill 

1 

2 

9 

13 
24 

Wichmann 

8 

22 

Total            

29 



37 

28 

95 

1 

It  is  imj^ossible,  then,  to  generalize  upon  the  effect  of  time  interval. 
Kepetition  of  turning  certainl}^  leads,  under  certain  circumstances, 
to  a  decrease  in  after-nystagmus.  But  that  the  decline  depends  in 
any  fixed  way  upon  the  length  of  the  temporal  interval  can  not  be 
maintained  upon  the  basis  of  the  evidence  at  hand.  The  decline  is 
not  to  be  laid  to  a  simple  process  of  adaptation  in  the  receptor  organs 
of  the  labyrinth,  for  such  sensory  adaptations  as  are  best  known — 
visual,  tactual,  and  thermal — are  of  brief  duration,  and,  furthermore, 
(hey  rapidly  disappear  with  the  lapse  of  stimulation.  Still  less  is 
the  effect  of  repetition  to  be  disposed  of  as  a  case  of  "  fatigue."  a 
term  which  the  uncritical  lay  reader  might  readily  suggest.  Nothing 
like  fatigue  (used  in  the  sense  of  waste  products  and  lowered 
metabolism)  is  here  observed;  and  the  proposal  of  that  term  as  an 
hypothesis  would  be  a  loose  use  of  the  argument  from  analog;y. 
which  explains  nothing.  If  genuine  fatigue  were  actually  induced 
by  rotation,  its  effects  would  scarcely  remain  unmodified  for  four 
or  five  days.  The  explanation  of  the  observed  decline  in  nystagmus 
remains,  therefore,  for  further  experimentati6n  made  under  more 
favorable  technical  conditions  than  the  department  has  been  able  to 
command.^ 

*  The  present  experiments  have  demonstrated  (1)  that  organic  dis- 
turbances tend  to  disappear  under  rotation  day  after  day  and  (2) 
that  the  after-nystagmus  is  reduced  in  violence  and  in  duration  under 
repetition  (a)  within  a  single  experimental  series — a  total  rotation 
of  about  three  minutes — and  (b)  day  by  day.  In  10  turning  days, 
with  10  observations  made  each  day,  the  average  decline  for  six 
subjects  was  approximately  15  seconds,  or  more  than  half  the  original 
duration  finally.     The  experiments  have  illustrated  (3)  the  fact  that 

1  Unquestionable  evidence  now  available  (see  editorial  insert  immediately  following) 
disproves  the  statement  that  "  repetition  of  turning  certainly  leads  to  a  decrease  in 
after-nystagmus."  Of  the  six  individuals  used  by  the  psychologic  department  for  these 
experiments  not  one  was  examined  physically  beforehand ;  two  of  these  six  were  dis- 
covered subsequently  to  be  pathologic,  the  other  four  had  meantime  been  lost  sight  of. 
This  failure  to  establish  positively  the  normality  of  the  individual  subjects  before  pro- 
ceeding with  the  series  of  tests  is  most  unfortunate  as  it  makes  it  impossible  to  draw 
any  scientific  conclusions  from  the  data  obtained. 


AIR   SERVICE    MEDICAL.  323 

casual  observation  of  nystagmus  involves  a  number  of  observational 
errors  which  may  be  eliminated  by  the  standardized  procedures  of 
tlie  psychological  laboratorj'. 

EDITORIAL   INSERT. 

The  foregoing  sets  forth  the  result  of  certain  ear  investigations 
which  were  undertaken  in  the  department  pf  psychology.  Neither 
the  findings  in  the  individual  cases  herein  reported  nor  the  deductions 
drawn  from  the  series  are  in  accord  Avith  the  findings  and  deductions 
of  the  otologic  department. 

Several  thousand  reexaminations  of  fliers,  made  by  skilled  otolo- 
gists who  have  been  occupied  with  daily  turning  chair  examinations 
of  the  internal  ear  for  unbroken  periods  covering  12  to  18  months,  do 
not  indicate  reduction  in  the  duration  of  nj^stagmus  following  rota- 
tion. A  carefully  analyzed  report  of  541  consecutive  cases  examined 
by  a  single  observer  on  three  of  the  southern  flying  fields  follows : 

One  hundred  and  fifty-six  men  examined.  Fl.ving  period,  0  to  25  hours. 
Average  nystagmus — turning  to  right,  25x*5%;  turning  to  left,  25 1^5^    seconds. 

One  hundred  and  sixty-nine  men  examined.  Flying  period,  25^  to  50  hours. 
Average  nystagmus — turning  to  right,  25  iV?;  turning  to  left,  251^^    seconds. 

Fifty-nine  men  examined.  Flying  period,  50*  to  75  hours.  Average  nystag- 
mus— turning  to  right,  19^^;  turning  to  left,  18|i  seconds. 

Thirty-seven  men  examined.  Flying  period,  75i  to  100  hours.  Average 
nystagmus — turning  to  right,  24|4 ;  turning  to  left,  25^  seconds. 

Twenty-one  men  examined.  Flying  period,  100*  to  150  hours.  Average 
nystagmus — turning  to  right,  25^;  turning  to  left,  25^^  seconds. 

Thirty-four  men  examined.  Flying  period,  150*  to  200  hours.  Average 
nystagmus — turning  to  right,  26^*5^;  turning  to  left,  25 :f\  seconds. 

Thirty-two  men  examined.  Flying  period,  200J  to  250  hours.  Average 
nystagmus — turning  to  right,  23^;  turning  to  left,  23if  seconds. 

Fourteen  men  examined.  Flying  period,  250*  to  300  hours.  Average  nystag- 
mus— turning  to  right,  23^^;  turning  to  left,  25^4^  seconds. 

Nineteen  men  examined.  Flying  period,  300i  to  1,000  hours.  Average  nys- 
tagmus— turning  to  right,  26x\;  turning  to  left,  25||  seconds. 

The  average  nystagmus  of  accepted  applicants  among  75,000  ex- 
aminations showed  on  turning  to  the  right,  23  seconds,  and  on  turn- 
ing to  the  left,  23.1  seconds.  It  will  be  noted  that  the  average  nystag- 
mus of  the  above  series  is  somewhat  higher.  It  will  also  be  shown 
by  the  fact  that  without  dividing  these  cases  by  the  hours  of  flying, 
the  average  on  turning  to  the  right,  was  24.6  seconds,  and  turning  to 
the  left,  24.4  seconds. 

A  series  of  daily  observations  made  by  otologists  who  have  had 
years  of  daily  practice  in  the  application  of  turning  chair  tests  of 
the  internal  ear  was  conducted  in  the  laboratory  at  Mineola.  The 
subjects  of  this  series  of  tests  were  10  adult  individuals  carefully 
determined  by  previous  physical  examination  to  be  normal.  (No 
evidence  exists  as  to  the  normality  of  four,  subjects  of  the  tests  con- 
ducted by  the  psychologic  department ;  the  other  two,  A  and  S,  were 
89118—19 22 


324 


AIR  SERVICE   MEDICAL. 


found  upon  physical  examination  to  be  pathologic.  It  must  be  espe- 
cially emphasized  that  pathologic  conditions  of  the  internal  ear  not 
affecting  hearing  may  be  of  a  nature  very  difficult  to  detect  by  ordi- 
nary observations ;  for  example,  the  sequelae  of  mumps,  lues,  typhoid 
fever,  and  other  acute  infectious  diseases.)  Six  subjects  were  turned 
each  morning  ( 10  turns  to  the  right  in  20  seconds  and  10  turns  to  the 
left  in  20  seconds)  and  four  subjects  were  turned  in  the  same  manner 
both  morning  and  evening.  It  was  noted  as  the  subjects  became 
accustomed  to  the  vertigo  induced  by  turning  that  with  the  profi- 
ciency attained  in  executing  voluntary  motor  coordinations  manifest 
in  pointing  tests  and  fall  tests,  a  commensurate  proficiency  be- 
came apparent  in  voluntary  fixation  of  the  gaze  through  daily  prac- 
tice. This  acquisition  of  an  increased  fixation  control  of  the  volun- 
tary eye  movements  resulted  in  a  lessening  of  the  duration  of  the 
resulting  nystagmus  in  some  cases.  That  this  was  in  no  sense 
the  result  of  change  in  character  or  intensity  of  the  vestibular  stimu- 
lus was  proven  by  placing  before  each  subject's  eyes  a  pair  of  plus 
20  lenses  which  rendered  fixation  of  the  gaze  impossible.  Observa- 
tions of  the  resulting  nystagmus,  made  not  only  through  these  lenses 
but  behind  them,  confirmed  beyond  question  the  finding  that  there 
was  no  reduction  in  the  duration  of  the  nystagmus  following  nine 
fteeks  of  uninterrupted  tests. 


FRE-i 

',  J.  C. 

Date. 

A.M. 

P.M. 

Date. 

A.M. 

P.M. 

Right. 

Left. 

Right. 

Left. 

Right. 

Left. 

Right. 

Left. 

Sept  26 

23 
20 
23 
21 
19 
20 
19 
20 
19 
20 
23 
17 
18 
21 
21 
20 
19 
22 
24 
19 

91 

22 
22 

26" 

19 
18 
21 
21 

21' 

17 
21 
19 

19' 

22 
19 
20 
18 
20 
18 
20 
18 

21 
24 
17 
19 
17 
18 
18 
21 
18 
20 
19 
19 
21 
19 
20 
18 
19 
21 
19 
19 
19 
19 
17 
19 

20 
28 

is 

18 
18 
19 
19 

is 

17 
20 
17 

i9 

23 
19 
18 
16 
18 
21 
21 
17 

Oct.  26 

20 
21 
19 
20 
25 
21 
19 
20 
22 
22 
24 
21 
21 
27 
21 

22" 

17 
19 
22 
17 

ig' 

19 

2i' 

26 
26 

25' 

2i* 

20 
21 
18 
21 
19 
IS 
20 
19 
19 
20 
21 
20 
18 
25 
19 
19 
20 
21 
20 
19 
19 
20 
20 
19 

27" 

28 

20 

28 

29 

16 

30 

30 

18 

Oct  1 

31 

19 

2 

Nov.  1 

16 

3 

3 

4 

4 

18 

5 

5 

18 

7 

6 

8 

7 

9 

8 

22 

11 

11 

20 

12 

12 

20 

14 

13 

15 

14 

19 

16 

16 

21 
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22 

17 

18 

18   

19 

21 

20 

20 

22 

21 

19 

23 21 

24 '    22 

25           5S 

22 

24 
23 
20 

20 

25 

26 

SCHNEIDER,  T.  G. 


Rpnt  28 

25 
26 
26 
29 
28 
19 
18 
23 

25' 

28' 

25 

26' 

20 
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25 
21 
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17 

Oct.   8 

20 
19 
21 
22 
19 
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28 

16 
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17' 

22 
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26 

18 
21 
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9 

20 

'<1 

10 

16 

npt   1 

12 

2 

14 

19 

4 

15 

21 

5 

16 

15 

7 

17 

21 

AlE  SERVICE   MEDICAL. 

SCHNEIDER,  T.  G.— Continued. 


325 


ENNIS,  L.  E. 


LONG,  C.  M. 


Date. 

A. 

M. 

P 

M. 

Date. 

A. 

M. 

P. 

M. 

Right. 

Left. 

Right. 

Left. 

Right. 

Left. 

Right. 

Left. 

t)ct.  18 

23 
19 
19 
17 
24 
20 
27 
27 
22 
26 
29 
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31 
21 

18 

is' 

20 
24 
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24' 

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24 
21 
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19 
i9 

18 
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30 

Nov.  7. 

26 
27 
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26 
26 
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25 
30 
28 
24 
27 
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30 
25 
27 

26' 

27' 

26 

25' 

23 
29 



21 
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24 
24 
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25 
20 
24 

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13 .» 

28 

25 

14.  .  . 

24 

26 

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16.  . 

29 

18 

30 

19 

21 

31 

20.  .  . 

20 

Nov.  1 

21 

21 

4 

22.  . 

5 

25 

6 

26 

Sept.  26 

26 
30 
30 
31 
24 
27 

26 
24 

25' 

24 
24 
23 

2i' 

22 

2i' 

21 
20 
29 
17 

20 
28 
26 
28 
22 
31 

ie" 

23 
26 
19 
21 
19 
21 
19 
23 
19 

19 
18 

25 

30 
26 
20 

ig 

19 

21 

19 
16 
23 
16 

Oct.  19 

18 
18 
25 
20 
22 
17 
28 
19 
23 
26 
20 
21 
28 
18 
28 
26 

20 
26 
16 
20 
18 

2i' 

30 
21 
24 

24' 

28 

18 
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21 
15 
25 
25 
25 
23 
24 
22 
24 
20 
29 
28 

^   27 

20 

20 

28 

22 

27 

30 

23 

20 

Oct.   2 

24 

20 

3 

25 

20 

4 

26 

5 

22 
20 
25 
24 
23 
24 
20 
20 
24 
22 

28 

23 

7 

29 

27 

10 

30 

25 

11 

31 

20 

12 

Nov.  3  .  . 

14 

4 

15 

6 

23 

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8 

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9 

18 

Sept.  26 

27 

26 
25 
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26 
25 
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17 
20 
18 
19 
20 
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16 
14 

24 
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27' 

23" 

25 
16 
14 

ie' 

18 

ii" 

19" 

22 

lY 

25 
18 
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26 
27 
22 
21 
23 
24 
21 
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18 
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■  19 
IS 
17 
19 

26 
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22 

26 

20 
16 
20 

16 

16 

ie 

ie 

18 

ie 

19 
16 
17 

Oct.  25 

15 
19 
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24 
IS 
23 
27 
18 
21 
18 
22 
21 
24 
25 
22 
25 
19 
26 
23 
18 
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20 

16 
19 
20 
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26" 

20 

21" 

20 

2i' 

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26' 



16 
18 
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21 
25 
21 
24 
18 
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30 
18 
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28  . 

18 

28 

29 

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30 

30 

20 

Oct.   1 

31 

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2 

Nov.  1 

24 

3 

3 

4 

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/......... 

10 

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326 


A.IR  SERVICE  MEDICAL. 

TRIMMER,  n.  M. 


Date. 


Sept.  26 

27 

28 

30 

Oct.      1 

2 

3 

4 

5 

7 

9 

10 

11 

12 

14 

15 

16 

17 

18 

19 

21 

22 

23 


Right. 

Left. 

24 

28 

20 

28 

26 

25 

25 

27 

27 

22 

22 

25 

21 

20 

18 

21 

21 

21 

20 

23 

20 

22 

24 

23 

18 

21 

24 

20 

18 

24 

20 

22 

19 

22 

24 

27 

25 

21 

24 

24 

20 

18 

21 

22 

22 

28 

Date. 


Oct.    24 

25, 

28 

29 

30 

31 

Nov.     1 

3 

4 

5 

6 

7 

8 

9 

11 

12 

13 

16 

18 

19 

21 

22 

26 


Right. 


Left. 


21 
21 
22 
25 
25 
28 
19 
20 
27 
24 
25 
20 
29 
22 
24 
24 
25 
26 
26 
22 
24 
22 
25 


24 
23 
23 
27 
25 
26 
23 
22 
26 
23 
23 
19 
28 
24 
30 
24 
21 
24 
28 
26 
23 
21 
21 


McCABE,  C.  J. 


Sept.  28, 

Oct.      1 

2, 

3, 

4, 

5. 

7. 

8, 

9, 

10, 

11. 

12 

14 

15 

16 

17 

18, 

21 

22 

23 

24 

26 


27 

27 

33 

25 

27 

27 

22 

23 

20 

19 

23 

20 

20 

21 

23 

21 

24 

24 

22 

22 

24 

23 

23 

20 

23 

22 

21 

19 

22 

24 

22 

23 

24 

19 

23 

23 

19 

24 

18 

21 

17 

19 

25 

24 

Oct.    28, 

29 

30 

Nov.     1, 

3 

5 

6 

7 

8 

9 

11 

12 

13 

14 

16 

18 

19 

21 

22 

23 

26 


22 
25 
23 
26 
26 
30 
27 
23 
21 
27 
25 
24 
27 
26 
24 
25 
26 
25 
21 
25 
24 


25 
28 
22 
29 
25 
30 
29 
21 
19 
26 
22 
21 
25 
28 
23 
22 
22 
24 
24 
23 
21 


BROWNING,  E.  L 


Sept.  26 

27 

2S 

30 

Oct.      1 

2 

3 

4 

5 

7 

8 

9 

10 

11 

12 

14 

15 

22 

23 

24 


26 

28 

22 

26 

24 

25 

27 

23 

25 

24 

27 

24 

22 

20 

22 

21 

21 

20 

23 

19 

21 

20 

22 

23 

25 

21 

16 

20 

20 

21 

23 

21 

20 

16 

24 

19 

22 

21 

16 

19 

Oct.    25 

26 
2S 
29 
30 
31 
Nov.  5 
8 
9 
11 
12 
13 
14 
16 
l.S 
19 
20 
21 
22 


20 
30 
26 
18 
22 
22 
27 
27 
25 
30 
25 
20 
26 
25 
23 
21 
24 
30 
26 


91 
28 
24 
19 
23 
27 
26 
26 
22 
30 
27 
23 
28 
26 
24 
22 
25 
30 
27 


AIR  SERVICE   MEDICAL. 
HAYMAN,  O.  C. 


327 


Date. 

Right. 

Left. 

Date. 

Right. 

Left. 

Sept.  28 

40 
38 
24 
31 
33 
31 
32 
30 
30 
32 
30 
23 
31 
26 
25 
27 
33 
23 
24 
34 
34 

37 
36 
30 
30 
30 
34 
34 
33 
30 
28 
32 
27 
30 
25 

25 

29 
32 
23 
27 
34 

Oct.  30. . 

28 
30 
30 
23 
26 
32 
30 
27 
29 
30 
29 
36 
29 
30 
30 
31 
28 
34 
30 
30 

29 

Oct.   2 

31 

20 

3 

Nov.  1.... 

2S 

7 

3 

27 

8 

4 

28 

9 

5 

31 

JO 

6 

26 

11 

l....i 

21 

12 

9 

26 

14 

11 

28 

15 

12 

26 

16 

13 

30 

17 

14 

27 

18 

16 

27 

19 

17 

27 

21 

18 

30 

23 ;. 

20 

28 

24 

21 

29 

25 

22 

25 

26 

26 

26 

29 

BRAMLEY,  R.  H. 


Sept.  28 

30 
29 
40 
25 
29 
24 
25 
29 
27 
22 
22 
25 
28 
27 
21 
19 
22 

33 
33 
31 
29 
29 
29 
26 
29 
28 
24 
21 
24 
26 
32 
22 
21 
28 

Oct.  23 

20 
19 
25 
21 
26 
28 
24 
25 
25 
27 
25 
26 
26 
35 
30 
32 

22 

Ont.   1 

25 

23 

2 

26 

31 

3 

28 

23 

7 

29 

28 

8 

30 

26 

9 

31 

28 

10 

Nov.  1 

24 

11  . 

3 

24 

12 

4 

28 

15 

5 

28 

16 

7 

29 

17 

8 

28 

18 

9 

37 

19 

12 

38 

21 

14 

30 

22 

JAFFA,  B.  B. 


Sept.  28 

26 
28 
34 
31 
28 
22 
26 
30 
27 
25 
25 
30 
20 
23 
20 
24 
24 
28 
22 

34 
31 
30 
31 
29 
26 
30 
33 
30 
25 
24 
30 
21 
21 
23 
23 
25 
27 
25 

Nov.  1 

26 
27 
26 
30 
25 
31 
31 
36 
30 
32 
29 
25 
27 
28 
28 
31 
31 
30 

26 

Oct.   2 

3 

27 

3 

4 

25 

11 

29 

12 

6 

27 

14 

7 

30 

15 

9 

28 

16 

11 

28 

18 

12 

28 

19 

13 

34 

21 

14 

30 

22 

16 

27 

23 

18 

26 

24 

19 

27 

25 

20 

26 

26 

21 

32 

28 

22 

29 

30 

26 

26 

31 

It  is  of  supreme  importance  for  the  reader  to  note  the  cardinal 
difference  between  the  series  of  541  examinations  of  fliers  here  re- 
ported, in  whom  no  reduction  in  the  duration  of  nystagmus  was  en- 
countered, and  the  turning  chair  tests  conducted  upon  10  subjects  for 
9  consecutive  weeks.  The  flier  can  not  practice  the  fixation  of  gaze 
owing  to  the  variability  of  conditions  under  which  he  flies;  the  sub- 


328  AIR  SERVICE   MEDICAL. 

ject  in  the  turning  chair  must  fix  his  gaze  accurately  after  each  turn- 
ing, thereby  undergoing  a  very  intensive  practice  in  gaze  fixation. 

It  follows,  therefore,  that  lohen  a  marked  reduction  in  duration  of 
nystagmu.^  is  encountered  it  must  he  regarded  as  indicating  a  deiinite 
departure  from  the  normid.  Examples  in  point  are  the  following 
three  cases: 

M,  flying  instructor,  reported  that  his  cadet  students  were  prone  to 
level  off  with  left  wing  down ;  officer  in  chargaof  flying  and  post  com- 
mander observed  that  M  always  leveled  off  with  the  right  wing 
doAvn.  He  was  ordered  up  for  physical  examination,  which  revealed 
pathologic  condition  of  his  internal  ear,  evidenced  among  other  find- 
ings by  6  seconds'  duration  nystagmus  after  turning  right. 

W,  a  flier,  who  had  been  determined  by  a  physical  examination  to 
be  normal ;  after  completion  of  flying  training  in  England  had  sev- 
eral months'  combat  service  on  the  western  front,  giving  daily  evi- 
dence of  satisfactory  flying  ability.  Officer  in  charge  of  flying  noticed 
gradually  increasing  loss  of  flying  abilit}'^ ;  three  weeks'  rest  was  not 
followed  by  the  expected  improvement,  and  he  was  ordered  up  for  a 
reexamination.  His  nystagmus  record  on  entering  flying  training 
was  26  seconds  after  right  turn,  26  seconds  after  left  turn;  on  this 
I'eexamination  it  was  found  to  be  7  seconds  right  turn,  9  seconds  left 
turn.  Further  examination  revealed  luetic  internal  ear  disease;  the 
aviator  then  stated  he  had  acquired  syphilis  since  admission  into  the 
service. 

Lieut.  X  under  flying  instruction,  was  reported  by  instructor  as  a 
very  dangerous  pupil,  having  repeatedly  leveled  off  with  left  wing 
down ;  instructor  refused  to  take  further  risks.  Officer  in  charge  of 
flying  upon  looking  up  record  of  physical  examination  found  that 
through  clerical  error  this  man  had  been  reported  fit  for  flying  train- 
ing instead  of  unfit  for  flying  training  owing  to  subnormal  nystag- 
mus following  turning.  In  all  tliree  of  these  cases  the  diagnosis 
of  internal  ear  abnormality  was  made  by  the  flying  instructor  solely 
upon  the  evidence  furnished  by  the  flier''s  performance  in  the  plane. 
Further  evidence  of  this  character  was  discovered  in  certain  of  the 
flying  fields  following  epidemics  of  mumps,  a  condition  affecting  the 
internal  ear  with  especial  frequency.     [End  of  editorial  insert.] 

2.  Orientation. — Methods  have  been  devised  for  determining  the 
promptness  and  the  accuracy  with  which  the  aviator  gets  his  bear- 
ings, finds  his  waj^  and  remembers  his  course  in  the  air.  The  abilit}^ 
to  keep  directions  and  to  maintain  a  correct  orientation  on  the  ground 
or  in  flight  differs  widely  from  individual  to  individual,  and  since 
both  personal  safety  and  successful  execution  depend  upon  clear  and 
prompt  orientation,  the  test  of  a  pilot's  ability  in  this  regard  is  of 
great  importance.  Various  typical  means  of  orientation  distinguish 
one  flier  from  another.     The  main  "types"  discovered  and  described 


AIR   SERVICE    MEDICAL.  329 

include  (1)  the  compass  type,  or  those  individuals  who  get  their  bear- 
ings by  the  cardinal  directions;  (2)  the  mapping  type,  individuals 
who  refer  places  and  directions  to  an  imaginary  map  upon  which 
north  is  always  before  and  east  at  the  right  of  the  observer;  (3)  the 
pointing  type,  W'hich  depends  upon  kinsesthetic  factors  for  orienta- 
tion ;  (4)  the  pathfinding  type,  which  relies  upon  the  recognition  of 
landmarks;  (5)  the  fragmentary  type,  which  is  oriented  only  in 
certain  regions  and  under  certain  circumstances;  (6)  the  disoriented 
type,  which  includes  the  habitually  confused  and  muddled;  and 
(7)  the  lost  type  of  individual,  who  takes  little  or  no  account  of 
spatial  clues  to  position  and  direction  and  who  can  not  be  trusted 
to  explore  new  regions  or  to  search  out  a  new  objective.  Both  the 
accuracy  of  exploration  and  the  appropriate  method  of  instruction 
in  map  making  and  map  reading  and  in  reconnaissance  depend  upon 
the  flj^er's  orientational  type. 

Apparatus  (figs.  20  and  21)  has  been  built  in  the  laboratory  for 
discovering  whether  the  pilot  or  the  observer  is  easily  lost  or  dis- 
oriented, whether  he  knows  and  keeps  his  compass  points,  and 
whether  he  is  capable  of  translating  verbal  orders  to  fly  to  a  named 
objective  into  a  plan  of  flight,  or  of  charting  a  terrain  from  his 
aerial  observations,  or  of  retracing  his  course  of  flight  by  the  observa- 
tion of  landmarks. 

The  test  of  the  methods  evolved  has  made  it  evident  that  it  is  pos- 
sible to  determine  within  a  few  minutes  the  "type"  of  the  aviator 
with  respect  to  orientation,  and  also  his  facility  in  getting  his  bear- 
ings and  in  maintaining  his  directions  under  the  exigencies  of  flight. 

3.  Association  reaction  times. — A  large  amount  of  work  has  been 
done  on  the  association  reaction  test  using  the  chronoscope  and  voice 
keys  (fig.  22).  In  this  test  a  word,  "stimulus  word"  spoken  by  the 
psychologist,  starts  the  hand  of  the  chronoscope  in  rotation,  and  a 
word,  "  response  word  "  spoken  by  the  reactor,  stops  the  hand.  The 
time  between  stimulus  and  reaction,  the  time  required  to  "  think  of 
the  reply  "  is  then  read  directly  on  the  dial  in  thousandths  of  a  second, 
psychologist,  starts  the  hand  of  the  chronoscope  in  rotation,  and  a 
response  word  of  definite  rotation  to  the  stimulation  word  (e.  g., 
verb  naming  action  which  could  be  exerted  by  whatever  is  desig- 
nated by  the  noun)  is  required.  In  this  way  a  rating  on  the  basis  of 
the  time  required  for  the  answer,  and  also  on  the  reliance  and  specific 
appropriations  of  the  answers  is  possible.  These  vary  according  to 
the  general  mental  ability  and  the  particular  condition  (fatigue,  etc.) 
of  the  reactor.  So  far,  the  work  has  been  largely  directed  to  the  de- 
velopment of  standard  lists  of  stimulus  words  (which  in  itself  re- 
quires a  large  amount  of  research)  and  the  perfecting  of  a  rating 
scheme. 


330  AIE  SERVICE   MEDICAL. 

The  foregoing  enumeration  by  no  means  exhausts  the  immedi- 
ate possibilities  and  needs  of  investigation  of  the  points  of  general 
and  special  fitness  and  adaptability  noted  in  an  earlier  sunnnary 
(Chap.  I).  Nor  does  it  include  all  the  work  on  these  topics  which 
is  under  way  in  the  psychological  laboratory.  It  indicates,  however, 
the  scope  of  the  work  in  the  direction  of  classificatory  tests,  and  to- 
gether with  the  preceding  statements  will  serve  as  a  guide  to  psycholo- 
gists in  the  various  fields  in  observing  fliers  and  flying  conditions  and 
collecting  information  useful  for  further  development  of  practical 
aid  to  the  service. 

VII.— DEPARTMENT  OF  NEUROLOGY  AND  PSYCHIATRY. 

The  work  of  this  department  touches  the  aviation  problems  at 
three  vital  points:  (1)  By  the  detection  in  the  aviator  of  symptoms 
of  nervous  and  mental  diseases;  (2)  by  the  recognition  of  latent 
trends  of  temperament  which,  if  not  recognized  in  time  and  treated 
rationally,  increase  the  liability  of  the  flier  either  to  become  ineffi- 
cient or  to  lose  morale  and  esprit  de  corps,  and  (3)  finally  by  supple- 
menting the  information  already  obtained  in  other  departments  in 
regard  to  the  aviator's  potential  fl.ving  capacity  with  additional  data 
bearing  upon  his  temperament  and  personality.  This  knowledge  to 
be  used  in  the  selection  of  fliers  for  special  tasks. 

The  examiner  should  keep  constantly  before  his  own  mind  the 
fact  that  the  chief  purpose  of  these  personality  studies  is  to  determine 
the  fitness  of  an  aviator  to  withstand  the  nervous  strain  of  flying 
at  the  front.  For  this  reason,  although  clinical  methods  of  examina- 
tion are  used  in  taking  these  histories,  they  should  not  be  judged  by 
ordinary  clinical  standards — as  the  purpose  is  not  to  carry  the 
analysis  of  the  aviator's  personality  further  than  is  necessary  to 
estimate  his  potential  as  a  flier  under  war  conditions. 

The  chief  sources  of  information  for  data  upon  which  judgment 
of  the  personality  is  based  are  (1)  the  Aviator  under  examination, 
(2)  other  Departments  in  the  laboratory,  (3)  the  Flight  Commander, 
and  (4)  the  Flight  Surgeon.  A  spirit  of  sympathetic  cooperation  is 
necessary  in  gathering  this  data  and  neurologists  and  psychiatrists 
should  remember  they  are  attempting  merely  to  supply  some  of  the 
links  in  a  relatively  long  chain  of  evidence. 

In  estimating  the  nervous  capacity  to  withstand  strain  the  ex- 
aminer should  give  particular  attention  to  the  following  points: 

(1)  What  were  the  chief  reasons  influencing  the  aviator  in  choos- 
ing this  branch  of  the  service?  Did  the  love  of  adventure,  desire  for 
independent  action,  or  interest  in  machinery,  or  a  combination  of  all 
these  elements  enter  into  the  decision?  Does  he  feel  that  he  is 
making  good  and  is  he  satisfied  with  his  original  decision?     The 


AIE    SERVICE   MEDICAL.  331 

statements  of  experienced  aviators  show  how  much  success  in  fly- 
ing depends  upon  making  that  particular  decision  clean  cut  and 
then  accepting  it  as  final.  Indecision,  a  sense  of  inadequacy,  or  idle 
regret  at  having  chosen  work  for  which  he  is  not  fitted  tempera- 
mentally may  lead  to  a  chain  of  symptoms  culminating  in  a  psychosis 
or  psychonciirosis. 

(2)  Impressions  of  the  aviator's  readiness  or  disinclination  to  face 
difficult  situations  fairly  and  squarel}'  shotild  be  recorded.  Evidence 
of  a  tendency  to  dodge  critical  events  in  life,  a  habit  which  if  not 
corrected  may  become  the  starting  point  for  morbid  fears  and  ob- 
sessions, should  be  noted.  An  experienced  and  daring  aviator  may 
lose  nerve  suddenly  as  the  result  of  not  having  definitely  settled  some 
relatively  trivial  event  of  a  personal  nature.  States  of  irresolution 
and  doubt  as  well  as  compulsions  antagonistic  to  efficiency  often 
develop  out  of  buried  mental  complexes. 

(3)  The  question  should  be  asked  whether  the  members  of  the 
immediate  family  approve  or  disapprove  of  his  flying,  making  it 
easy  or  difficult  for  the  aviator  to  devote  his  entire  attention  to  his 
work. 

(4)  Notice  should  also  be  taken  of  the  occurrence  of  nervous  or 
mental  disorders  in  the  family  history. 

Associated  with  the  effort  to  present  brief  records  containing  only 
(he  essential  facts  in  each  case,  there  should  also  be  a  clear  apprecia- 
tion of  the  number  and  variety  of  factors  which  may  affect  the  be- 
havior of  the  aviator.  Each  analysis  should  be  based  on  the  consid- 
eration of  the  active  forces  influencing  behavior  in  critical  situations. 
The  restriction  of  the  investigation  merely  to  taking  a  cross  section  of 
life  at  any  single  level  in  the  life  curve  is  not  sufficient.  Remotely 
antecedent  events  in  life,  such  as  attacks  of  disease,  accidents,  circum- 
stances giving  rise  to  bad  habits,  or  poor  educational  opportunities, 
may  have  a  direct  practical  bearing  on  the  performances  of  the 
aviator  in  a  plane. 

The  following  cases  are  cited  to  illustrate  the  advantages  of  a  very 
brief  summary  of  the  life  history. 

Case   1.— Personality   rating,   "A."     No  indication   that   he   will   require   any 
special  attention  nor  be  predisposed  to  collapse  under  strain. 

,  1st  lieut,  A.  S.  S.  C. 


Aviation  history :  No  "  repeats "  in  ground  school.  Licensed  pilot.  80  hrs. 
flying  to  date.     No  accidents. 

Personal  history :  No  serious  illness  nor  accidents.  Public-school  education ; 
not  college  graduate.  Has  worked  hard  for  living  and  enjoyed  it.  No 
grouches.  Normally  optimistic.  Advised  by  his  captain  in  Infantry  to 
transfer  to  aviation.    Glad  he  did  so;  enjoys  flying;  feels  he  is  making  good. 

Physical  examination :  Height,  5  ft.  6  in. ;  weight,  132 ;  age,  23.  Nothing 
{ibnormal, 


332  AIR  SERVICE   MEDICAL. 

Tests  (low  tension)  :  Very  good,  "A." 

Personality  study:  Stocky,  muscular  type;  look  steady,  countenance  cheerful, 
but  not  overemotional.  Activity,  good ;  discipline,  good ;  willing  to  take 
chances  if  necessary.  Stability  under  strain  probably  excellent.  Good 
judgment. 

Case  2. — Personality  rating,  "  B."    Safe  if  watched  for  development  of  nervous 
symptoms. 

,  flying  cadet,  A.  S.  S.  C. 


Aviation  history :  Ground  school ;  difficulty  with  wireless  (has  poor  musical 
sense).    8  hrs.  flying  to  date.    No  accidents. 

Personal  history :  Nothing  of  importance  in  family  history  except  "  mother 
worries  greatly  about  me  "  and  writes  to  him  on  this  subject.  College  gradu- 
ate (4  yrs.),  Harvard,  A.  B. ;  worked  his  way  through  college  and  has  also 
worked  in  munition  factory.  No  pronounced  reasons  given  for  choosing 
aviation.    Unmarried. 

Physical  examination :  Height,  5  ft.  6  in. ;  weight,  140  lbs, ;  age,  24.  Nothing 
abnormal  noted. 

Tests  (low  tension:  — . 

Personality  study:  Short,  well  knit;  regular  features,  mobile,  expression  tense 
but  under  control ;  anxious  to  understand  and  please.  Manner  tense  and 
high  strung.  Keen  sense  of  responsibility.  Ambitious  and  keenly  interested 
in  his  work,  but  inclined  to  take  even  trivial  events  too  much  to  heart.  Will 
do  his  duty  but  needs  careful  watching  when  he  gets  to  the  front.  Should 
be  watched  for  signs  of  staleness  or  beginning  nervousness,  loss  of  sleep,  etc. 

Case  3. — Personality  rating,  "  D,"    Probably  not  safe  if  flying  at  the  front. 


Aviation  history :  No  trouble  In  ground  school ;  work  in  ground  school  described 
as  easy. 

Personal  history.  Bright  at  bookwork ;  high-strung  always ;  exceedingly  popular 
with  friends.  Has  had  most  of  children's  diseases;  no  complications  nor 
accidents.  Great  interest  in  athletics.  Public  schools  and  college.  Entered 
service  from  junior  class.    Unmarried. 

Physical  examination :  Very  active  knee  jerks.  Pupils  show  secondary  expan- 
sion, after  dilatation.    Height,  6  ft. ;  weight,  155 ;  age,  24. 

Tests  (low-tension)  : 

Personality  study:  Decidedly  self-conscious;  slightly  aggressive  manner;  very 
high-strung  and  overemotional.  Lacks  normal  subjective  feeling  of  fatigue 
after  hard  exercise.  Talks  a  great  deal  and  rapidly.  Gives  the  impression 
of  working  under  great  pre.ssure.  Is  decidedly  nervous  and  lacks  voluntary 
control  of  expenditure  of  energj'.  Reserve  store  of  energy  limited.  Would 
probably  not  stand  strain  of  active  service  at  the  front. 

Accompanj'ing  each  history  a  personality  summary  is  made  on  a 
separate  slip  in  order  to  present  the  essentials  in  as  brief  form  as 
possible  for  the  use  of  the  Commanding  Officer.  If  more  detailed  in- 
formation is  required,  this  can  be  obtained  by  reference  to  the  labora- 
tory records. 


Am  SERVICE   MEDICAL.  33,3 

Personality  Summary.     No.  — . 
hazelhurst  field,  mineola,  n.  t. 


Aviation  history 

Personal  history , 

Physical  examination 

Tests   (low-tension) 

Personality  study 

Rating: 

Personality 

Tests   (low-tension) 

A  summary  of  the  cases  already  examined  in  this  department  with 
an  explanation  of  ratings  follows. 

The  object  of  the  personality  study  is  to  determine:  (1)  Whether 
neuroses  or  psychoses  actually  exist  or  (2)  whether  there  are  any 
indications  in  the  temperament  or  personality  of  the  aviator  sug- 
gesting that  tendencies  now  latent  under  the  stress  of  war  conditions 
may  give  rise  to  symptoms  of  nervous  shock,  diminishing  efficiency 
and  impairing  morale. 

Personality : 

"A". — Safe.     Nervous  and  mentally  stable. 

"  B  ". — Safe,  with  limitations. 

"  C  ". — Questionable ;   no  definite  conclusion  reached. 

"  D  ". — Needs  special  attention. 

"  E  ".—Unsafe. 

Not  rated. 
Tests  (low- tension) : 

"A". — No  restrictions. 

"  B  ".—Should  not  fly  above  15,0(X)  feet. 

"  C  ".—Should  not  fly  above  '8,000  feet. 

"  D  ".—Should  not  fly  at  all. 
Personality  studies: 

Rating   "A" 46 

Rating   "  B  " 29 

Rating  "  C  " 16 

Rating  "  D  " 1 

Rating  "  E  " 1 

Not  rated 18 

Total _ 111 


334  AIR    SERVICE   MEDICAL. 

Low-tension  tests: 

Rating  "A" 27 

Rating  "  B  " 26 

Rating  "  O  " 14 

Rating  "  D  " 6 

Not  rated _  38 

Total 111 

Agreement,  personality  rating,  and  tests 36 

Nonagreenient  personality  rating  and  tests 29 

One  or  both  ratings  absent 46 

Total 111 

The  discrepancies  noted  between  personality  ratings  and  test  rat- 
ings are  no  evidences  of  marked  differences.  The  low-tension  tests 
are  made  with  the  object  of  determining  the  aviator's  capacity  to 
meet  changes  incident  to  variations  in  barometric  pressure,  whereas 
the  aim  of  the  personality  studies  is  to  determine,  if  possible,  the 
resisting  capacity  for  nervous  and  mental  shocks. 

In  collecting  this  material  for  records  great  care  should  be  taken 
not  to  suggest  imaginery  troubles  to  the  person  being  examined. 
Babinski  and  Froment  (Hysterie-Pithia-tisme  et  troubles  nerveux 
d'ordre  reflexi  Collection  Horizon.  Precis  de  Medicine  et  de  Chir- 
urgie  de  (juerre,  Masson  &  Cie.,  1918)  have  emphasized  the  increased 
danger  of  "  suggestion  "  as  an  etiological  factor  of  nervous  diseases 
in  the  life  of  the  soldier.  A  great  deal  therefore  depends  upon  the 
tact  and  good  judgment  of  the  examiner. 

A  A^ery  important  function  of  the  work  of  the  department  is  to 
make  clear  the  value  of  good  mental  Iwgiene  in  increasing  efficiency 
in  assisting  in  the  maintenance  of  discipline  on  rational  grounds  in 
strengthening  morale  and  contributing  to  the  esprit  de  corps  essen- 
tial for  a  complete  and  final  military  victory. 

Informal  conferences  on  the  subject  of  the  mental  hygiene  of  the 
aviator  should  be  of  practical  value.  The  demoralizing  influences 
of  intemperance,  using  the  word  in  a  abroad  physiologic  sense,  the 
paralyzing  effects  of  worry  over  unsolved  personal  problems,  of  the 
failure  to  get  square  with  life,  of  anxiety  about  anticipated  events, 
and  the  shock  caused  by  suddenly  awakening  to  the  realization  of 
the  fact  that  the  lure  of  wish-directed  thoughts  make  an  individual 
incapable  either  of  judging  or  facing  reality. 

The  casualty  list  in  the  Aviation  Service  can  be  greatly  reduced 
hy  insisting  upon  the  necessity  of  cultivating  a  frank,  open  attitude 
of  mind  in  the  treatment  of  the  various  problems  which  are  forced 
upon  the  attention  of  the  flier.  Staleness,  loss  of  confidence,  various 
phobias,  and  increasing  emotional  instability  are  insidious  enemies. 


LoRcnt 


Pul; 


-•    R 


t  f  p.   m  dcMl.   p(  r  mm. 


:.t.  B    P, 


Syst.  B.  P 


D.R.,    Ape:    20-6/12  ■'     '^ 

Ui-tral  Rteno'-^ip  ar^i  insufficiency.  High  '  t  ,  , 
pulse  and  bloo'l-Fresruro.  labored  res-  _i._.j.._l_ 
ptratlcn.        Fal'.'ng   disFtollc   precpur©  i     i    <     !     L    i     >     I 

at  end   ir.dica^irg  circulatory   exhaustion,    '     v' 1     |     !     |     :     i 

^rni  rti- 

I       I       I       I       I       :       :         '     '       ! 


'     "    I)    1    ■> 


No.  217. — D.  K. 


CADET. 


Age  20  years,  6  months. 


There  was  a  roughening  of  the  first  heart  sound  heard  before  the  test.  No  demonstraliie 
enlargement,  second  sounds  equal.  During  the  test  a  definite  systolic  murmur  developed 
and  the  pulmonic  second  was  accentuated.  There  Is  no  doubt  of  the  diagnosis  of 
mitral  iusutHciently  well  compensated. 

The  chart  is  typical  of  most  cases  of  valvular  lesions.  The  pulse  is  high  tliroughout 
the  test.  The  systolic  pressure  is  high  and  uniform.  Diastolic  pressure  begins  to  fall 
between  9  and  10  per  cent,  but  is  in  control  at  all  times.  Respiration  shows  rather  a 
marked  response.  Efficiency  is  well  preserved,  the  psychological  note  being  A.  This 
is  accomplished  at  the  expense  of  marked  overwork  of  the  heart.  Although  this  is  well 
borne  at  the  present  time,  the  presumption  is  that  the  subject  would  soon  show  the 
effects  of  wear,  jind  permanent  damage  to  the  heart  might  easily  result.     Class  D. 


205 


205 


ATR  SERVICE   MEDICAL.  335 

Aviators  should  be  familiar  with  the  methods  of  preventing  the 
formation  of  some  of  the  mental  influences  disorganizing  both  to 
temperament  and  character.  The  difficult  task  of  keeping  their  nerve 
should  not  be  made  unnecessarily  difficult  by  the  failure  to  appreciate 
and  apply  a  few  of  the  principles  of  good  mental  hygiene. 

HELPING  THE  AVIATOR  TO  KEEP  HIS  NERVE. 

No  one  doubts  the  desirability  of  maintaining  within  the  aeroplane 
and  its  motor  the  conditions  essential  for  maximum  flight  efficiency. 
There  are  only  a  few  people,  however,  who  recognize  the  necessity 
for  detecting  and  remedying  the  disturbances  of  the  delicate  nervous 
and  mental  adjustments  of  the  aviator  controlling  the  machine. 
In  the  air  service  of  the  allied  armies  the  lists  of  casualties  due 
to  preventable  and  unknown  causes  are  very  much  longer  than  the 
ones  containing  the  names  of  aviators  killed  in  battle.  Many  of  these 
fatalities  are  due  to  the  failure  of  those  directing  the  activities  of 
the  aviator  to  take  cognizance  of  his  imperfect  emotional  and  mental 
adjustments. 

A  long  list  of  accidents,  however,  is  not  the  only  deplorable  effect 
of  the  failure  to  assist  the  aviator  to  keep  his  nerve  and  his  head 
in  critical  situations.  The  human  machine  loses  efficiency  much  more 
rapidly  through  neglect  to  provide  the  conditions  essential  for  good 
headwork  than  the  motor  does  when  it  is  not  well  oiled  or  its  parts 
are  not  kept  thoroughly  adjusted.  If  even  half  as  much  care  as  is 
now  given  the  machinery  of  the  planes  was  devoted  to  finding  out 
whether  the  emotional  and  mental  balance  of  the  aviator  was  equal 
to  the  strain  to  which  it  is  subjected  it  would  be  possible  to  develop 
the  fighting  efficiency  of  the  air  forces  to  a  much  higher  degree  than 
exists  at  present. 

The  aviator  in  action  has  to  be  heart  and  soul  in  his  work.  Neither 
his  attention  nor  interests  can  be  divided,  even  for  an  instant. 

Very  brief  periods  of  distractibility,  uncertainty,  or  slight  anxiety 
at  critical  moments  may  end  quickly  in  a  catastrophe.  In  many  occu- 
pations, even  in  military  life,  these  momentary  lapses  may  not  end 
disastrously,  but  the  chances  of  their  doing  so  while  the  aviator  is 
in  the  air  are  a  thousand  times  greater.  The  emotional  and  mental 
balance  of  the  aviator  should  be  so  very  delicately  adjusted  that  it 
responds  instantly  and  accurately  whenever  the  unexpected  strain 
of  the  critical  situation  is  thrown  upon  it.  The  aviator  has  practically 
no  opportunity  to  correct  his  mistakes.  A  wrong  impulse,  uncon- 
trolled emotion,  or  thought  not  related  to  the  situation  may  be  the 
cause  of  disaster.  This  principle  is  equally  true  whether  the  aviator 
is  high  in  the  air  or  approaching  the  ground. 

Disasters  resulting  from  hesitation  or  indecision  in  the  compara- 
tively difficult  though  necessary  procedure  of  landing  may  be  and 


336  AIR  SERVICE   MEDICAL. 

undoubtedly  are  often  due  to  a  certain  mental  or  nervous  instability 
not  generally  demonstrated  by  the  ordinary  methods  of  observation 
or  medical  supervision.  These  disturbances  of  the  mental  balance 
are  demonstrable  and  capable  of  being  ameliorated  by  neurologic 
or  psychiatric  methods.  The  dangers  of  indecision  or  divided  atten- 
tion when  in  combat  or  even  when  in  the  usual  "  formations,"  now 
the  rule  in  aerial  warfare,  may  be  easily  visualized  and  can  hardly 
be  overestimated.  In  the  illustration  (the  jackals,  p.  19)  the  im- 
portance of  maintaining  position  in  "  formation "  is  emphasized. 
This  maneuver  requires  great  mental  alertness  and  good  judgment. 
The  danger  of  possible  collision  with  other  fliers  in  the  "  formation  " 
can  only  be  avoided  by  unswerving  attention  and  coordinated  and 
instantaneous  action. 

What  are  some  of  the  causes  which  lead  to  momentary  but  often 
fatal  inefficiency?  Anxiety,  worry,  straining  to  repress  harassing 
memories  of  personal  trouble,  a  sudden  and  temporary  but  over- 
whelming sense  of  inadequacy  in  facing  a  crisis  very  often  interfere 
with  the  transmission  of  the  coordinated  motor  impulses  from  the 
brain.  An  aviator  having  an  excellent  record,  though  trying  hard 
but  unsuccessfully  to  repress  any  recollection  of  worry  over  personal 
problems,  may  lose  his  nerve  and  refuse  to  fly,  or,  on  the  other  hand, 
he  may  attempt  to  fly  while  the  mental  conflict  is  still  acute  and  end 
his  career  with  a  fatal  crash.  An  aviator  struggling  hard  to  repress 
and  forget  these  nerve-wrecking,  disorganizing  ideas  and  anxieties 
is  a  menace  to  himself  and  the  whole  organization  until  by  frankly 
talking  the  matter  over  with  some  sensible  person  he  "  gets  it  off  his 
chest."  The  first  step  in  the  restoration  of  efficiency  and  nerve  con- 
sists in  facing  squarely  the  real  cause  of  his  anxiety  instead  of  try- 
ing to  evade  it. 

Even  the  aviator  who  is  mentally  and  physically  fit,  may  be  thrown 
into  a  condition  of  mental  irritability  and  anxiety,  which  he  is  not 
able  to  control,  upon  the  receipt  of  depressing,  unreasonably  solicit- 
ous, or  even  threatening,  letters  from  home.  Frequently  states  of 
apprehensiveness  and  anxiety  affect  the  aviator  to  a  far  greater  ex- 
tent than  he  realizes  or  is  willing  to  admit  even  to  himself. 

There  are  different  types  of  personality  which,  on  account  of  their 
special  intellectual  qualities,  are  now  generally  recognized  as  possess- 
ing the  temperamental  qualities  antagonistic  to  success  in  aviation. 
Among  the  types  which  require  special  supervision  are  men  with 
decided  variations  in  mood  or  emotional  tone.  We  all  know  men,  in 
our  own  circle  of  acquaintances,  in  whom  such  variations  are  marked ; 
men  who  may  be  classed  at  times  as  extreme  optimists,  at  other  times 
swinging  over  to  the  opposite  or  pessimistic  pole  of  emotional  ex- 
perience.    Within  certain  limits  and  under  intelligent  medical  super- 


AIB   SERVICE   MEDICAL.  337 

vision,  this  group  of  men  may,  and  probably  do.  furnish  some  of  the 
most  versatile  and  daring  of  the  aviators.  On  the  other  hand,  we 
are  confronted  by  the  fact  that  these  same  men  if  permitted  to  swing 
to  the  extremes  of  the  emotional  arc  will  certainly  become  casuals 
or  casualties.  They  may  develop  on  the  one  hand  into  the  cases  of 
unbalanced  manic-depressive  make-up,  latent  hj'sterical  trends,  and 
many  cases  showing  symptoms  of  the  anxiety  neuroses. 

The  question  of  mental  hygiene,  as  relatecl  to  the  aviator,  should  be 
given  a  great  deal  of  attention.  The  reduction  of  the  efficiency  of 
the  soldier  through  any  form  of  intemperance  is  now  generally 
recognized;  and  similar  effects,  but  to  a  far  greater  extent,  are  ob- 
served in  the  case  of  the  aviator.  The  type  of  man  making  the  suc- 
cessful aviator  is  often  high  strung  and  impulsive  and  requires 
plenty  of  outlet  for  his  energies.  These  outlets  can  be  easily  pro- 
vided in  ways  entirely  satisfactory  to  him  and  conducive  to  his 
efficiency  without  injuring  the  brain  and  the  nervous  system  as  does 
dissipation.  He,  himself,  does  not  seek  dissipation;  but,  having  an 
enormous  amount  of  unexpended  energy,  he  seeks  some  channel — any 
channel — for  its  discharge.  Adequate  provision  should,  therefore,  be 
made  for  recreation  and  suitable  forms  of  mental  relaxation  if 
the  dangers  of  dissipation  are  to  be  avoided. 

The  supervision  of  the  aviator  outlined  above  has  been  definitely 
included  as  a  part  of  the  duties  of  the  Flight  Surgeons.  It  is  planned 
that  the  Flight  Surgeons  shall  receive  instruction  and  advice  rela- 
tive to  the  methods  of  observation  and  examination  of  the  fliers  at 
the  Medical  Research  Laboratory  or  other  centers  of  instruction. 
That  specialists  in  psychiatry  can  not  be  trained  in  the  short  time 
available  is  clearly  recognized.  On  the  other  hand  it  is  possible  for 
the  Flight  Surgeon  to  obtain  a  certain  point  of  view  toward  his  prob- 
lem and  for  him  to  become  definitely  informed  concerning  the  types 
of  personality  referred  to  in  the  preceding  paragraphs.  The  prob- 
lem of  the  training  of  the  Flight  Surgeon  therefore  resolves  itself 
into  one  of  method  of  observation  and  examination. 

The  neuro-psychiatric  examination  is  brief;  sufficiently  brief  to 
get  it  all  on  one  page.  First  is  given  an  account  of  the  aviator's  en- 
trance into  the  Air  Service,  of  his  aviation  school  work,  and  the 
chief  causes  which  led  to  his  selection  of  this  branch  of  the  service. 
It  is  important  to  know  whether  the  choice  of  this  branch  of  the 
service  was  made  voluntarily  and  enthusiastically;  whether  he 
drifted  into  it  and  is  more  or  less  indifferent  or  even  unhappy  in  it. 
Then  follows  an  account  of  his  Army  life  preceding  his  entrance 
into  aviation.  Finally  in  this  part  of  the  investigation  a  note  is 
made  of  the  number  of  hours  of  flying,  and  also  whether  there  have 
been  any  accidents.  A  brief  personal  history  follows  the  family 
history,  with  reference  to  the  diseases  or  injuries  he  has  had.    Com- 


338  AIB  SERVICE   MEDICAL. 

paratively  slight  disorders  may  be  the  cause  of  great  harm.  Ton- 
sillitis is  an  example.  Attention  is  paid  to  his  school  and  college 
record,  with  mention  of  his  athletic  record.  These  data  tell  us  some- 
thing as  to  the  sports  in  which  he  was  proficient  and  give  us  a  fair 
idea  of  his  skill  as  well  as  of  his  temperament  qualities. 

The  attitude  of  the  family,  especially  the  mother  and  wife,  are 
noted,  whether  it  is  one  of  sympathetic  approval  or  disapproval,  and 
this  has  an  important  influence  upon  his  capacity  to  keep  his  nerve. 
We  also  try  to  ascertain  whether  he  has  definite  cause  for  worry. 
Sometimes  there  are  periods  when  the  aviator  prefers  not  to  fly,  but, 
on  the  other  hand,  he  is  usually  very  keen  for  his  work,  and  it  is  only 
when  something  has  gone  wrong  that  his  enthusiasm  wanes;  some- 
times disturbing  influences  emanate  from  home;  sometimes  he  feels 
"  fed  up  "  and  wants  a  holiday.  Many  influences,  both  internal  and 
external,  may,  if  powerful  at  the  critical  moment,  throw  him  off  his 
mental  balance.  The  aviator's  balance  and  alertness  must  be  main- 
tained at  the  highest  efficiency  while  he  is  flying.  At  intervals,  when 
for  any  reason  his  full  potential  efficiency  is  not  maintained,  he 
should  not  fly  nor  until  he  is  again  at  his  best,  both  physically  and 
mentally.  Great  tact  should  be  exercised  in  gathering  the  data.  A 
great  deal  of  information  of  importance,  often  of  a  personal  nature, 
would  not  be  divulged  unless  the  exam.ination  brought  it  easily  to 
light  and  demonstrated  to  the  aviator  its  importance. 

Third,  a  brief  physical  examination  is  riiade.  The  reactions  of  the 
pupils  and  extrensic  muscles  and  the  knee  jerks  for  evidence  of 
hypertension  or  hyperexcitability  are  recorded.  Sometimes  we  get 
signs  of  fatigue  in  these  reactions;  sometimes  signs  of  emotional 
hyperactivity.  The  presence  of  tremor  in  the  extension  of  the  hands 
and  in  the  handwriting,  as  well  as  in  the  process  of  drawing  hori- 
zontal and  vertical  lines  freehand,  is  also  mentioned. 

Tests  for  dermagraphia  before  and  after  flying  or  before  and  after 
the  rebreathing  tests  are  made.  Definite  conclusions  relative  to  these 
tests  have  not  been  reached  as  yet,  but  our  attention  has  been  drawn 
to  certain  groups  of  symptoms.  We  have  looked  upon  a  tendency 
of  the  line  to  spread  or  blotch  as  rather  connected  with  other  signs 
of  fatigue  and  disability.  This  reaction  is  frequently  accompanied, 
though  not  always,  by  nervous,  veiy  lively  knee  jerks  and  an  emo- 
tional instability.  A  secondary  pupillary  reaction  is  sometimes  asso- 
ciated with  this  group  of  symptoms. 

Occasionally  after  the  rebreathing  or  after  flying  a  blushing  is 
observed  a  finger's  width  on  either  side  of  the  line.  This  seems  to 
be  of  more  or  less  importance,  taken  in  conjunction  with  the  other 
symptoms  mentioned.  But  whether  this  deduction  can  be  borne  out 
by  further  observation  remains  to  be  seen. 


AIR   SEEVICE   MEDICAL.  339 

Laatly,  we  record  our  impression  of  the  aviator's  personality.  We 
observe  Avhether  he  is  open  and  frank  in  his  talk  or  reserved  and 
inhibited.  We  note  his  emotional  state,  trying  to  determine  whether 
he  is  in  a  contented  frame  of  mind  or  whether  he  is  disgrmitled  and 
does  not  want  to  say  so  or  whether  he  is  "  fed  up."  It  is  important  to 
determine  as  closely  as  possible  what  the  reason  is  that  he  is  on  edge 
or  out  of  sorts.  With  this  object  in  view,  a  record  is  kept  of  even 
slight  fluctuations  of  moods.  * 

Frequently  we  run  across  men  in  a  state  of  mental  artxiety  mild 
or  acute.  A  little  tactful  questioning  will  usually  bring  out  the 
causes.  These  causes  may  be  simple  and  easily  removable,  or  they 
may  be  complicated  and  persistent.  The  points  bearing  on  the  case 
must  be  talked  over  frankly  and  conscientiously.  Late  hours,  loss  of 
sleep,  too  many  cigarettes  will  easiW  lower  the  resistance.  Worry 
and  anxiety  of  any  sort  in  the  otherwise  perfectly  healthy  and  w^ell- 
set-up  man  will  surely  reduce  his  efficiency.  Even  steady  attendance 
upon  his  work  to  the  point  where  he  is  "  fed  up  "  will,  if  persisted 
in,  produce  signs  of  mental  and  nervous  strain  and  sc^n  render  him 
a  danger  in  the  air. 

In  a  short  study  of  the  personality  we  determine  whether  the  flyer 
is  aggressive  or  on  the  defensive,  whether  he  has  initiative  and  cour- 
age or  is  reckless  and  irresponsible,  whether  he  makes  quick  or  slow 
decisions,  whether  he  is  a  high-pressure  engine  under  control,  and 
whether  his  judgments  are  likely  to  be  good.  His  reactions  during 
the  examinations  are  important.  He  may  give  active  cooperation, 
and  this  is  a  good  sign,  or  he  may  leave  us  with  the  impression  that 
the  result  of  the  examination  was  unsatisfactory;  even  this  indefi- 
nite finding  may  later  have  an  important  bearing  on  the  personality 
study  and  should  be  recorded.  These  and  other  items  help  us  to  gain 
a  fairly  definite  impression  of  our  man. 

Nervous  states  nearer  the  border  line  of  the  psychoses  are  occasion- 
ally observed.  The  importance  of  detecting  these  cases  and  weeding 
them  out  is  apparent,  and  we  should  appreciate  how  easily  they  may 
escape  recognition.  Many  cases  which  under  conditions  of  ordinary 
life  do  not  develop  into  psychoses  in  all  probability  will  take  this 
unfavorable  turn  under  the  strain  and  stress  of  war. 

Our  whole  object  is  to  determine  any  undesirable  psychomotor  or 
other  reaction  that  indicates  that  the  man  is  wholly  or  in  part  unfit 
for  flying.  We  accomplish  this  in  as  brief,  direct,  and  practical  a 
way  as  possible.  After  the  examination  the  man  is  classified  accord- 
ing to  estimated  efficiency,  judged  from  the  neurologic  and  psychia- 
tric point  of  view.     The  classifications  are  A,  B,  C,  D,  E. 

Explanation  of  personality  rating: 

A=Safe,  nervous,  and  mentally  stable. 
B— Safe,  with  limitations. 
89118—19 23 


340  AIB  SEEVICE  MEDICAL. 

C= Questionable;  no  definite  conclusion  reached. 

D= Needs  special  attention. 

E= Unsafe. 
In  order  to  illustrate  some  of  the  different  types  and  give  an  indi- 
cation of  the  methods  of  making  personality  studies  the  following 
cases  are  cited : 

PEEsoNAriTY  Recobd. — No.  194. 
.  White  Field,  N.  H.,  June  S,  1918. 

H.  R.  S.,  1st  It.,  RSSR.,  pilot. 

Aviation  history :  Officers'  Training  Camp  June  to  July  30,  1917 ;  ground  school 
to  Aug.  5,  1917 ;  to  E.  Field  to  Dec.  20,  1917 ;  to  J.  Field  March  31,  1918 ;  com- 
missioned Feb.  6,  1918;  to  S.  Field  to  date.  260  hrs.  flying  to  date.  No 
crashes. 

Personal  history :  Measles  and  scarlet  fever,  good  recovery.  Appendicitis  1915, 
operation  successful.  Father  dead,  age  53,  chronic  nephritis ;  mother  living 
and  well ;  1  sister  living  and  well.  Mother  does-  not  approve  of  aviation,  be- 
lieving it  too  hazardous  for  her  son.  Mother's  concern  has  "modified  his 
actions ;  more  careful."  This  is  doubtful.  Not  particularly  athletic.  Educa- 
tion, high  school  and  college. 

Physical  examination:  Ht,  69;  wt.,  136;  age,  24.  Knee  jerks  active.  Fine 
tremor  in  fingers,  constant ;  pupils  react  normally  to  light  and  accommodation. 
No  secondary  dilatation. 

Personality  study :  Quiet,  some  reserve ;  has  to  be  interested  in  flying  to  follow 
it  or  make  it  a  success;  deeply  interested  in  flying;  anxious  to  get  across; 
"  getting  tired  of  wasting  further  time  in  training."  Was  disappointed  three 
weeks  in  not  being  transferred  to  Columbus  and  in  not  getting  leave  of  ab- 
sence. Wants  aerial  gunnery ;  has  had  100  hrs.  formation ;  getting  disgusted ; 
feels  physically  tired  from  continued  flights  and  frequent  trips  to  New  York. 
(Impatient.)     Emotion  easily  excited  toward  end  of  examination. 

Rating :  Personality,  "  E."    Tests,  low-tension. 

Peesonality  Recokd. — No.  207. 

Station ,  Date . 

B.,  R.,  2d  lieut.,  —  squadron,  pilot. 

Aviation  history :  Enlisted  aviation  section  Sept.,  1917 ;  graduated  from  ground 
school  Jan.  20,  1918;  Kelly  Field,  San  Antonio,  Tex.,  to  June  10,  1918; 
to  R.  F.  to  date.  150  hrs.  flying  to  date.  2  accidents.  2  crashes,  both 
from  low  altitude  in  high  wind,  2  days  following  first  solo  flight.  Not 
injured. 

Personal  history:  Father  and  mother  alive  and  well.  Glad  to  have  him  in 
aviation.  Athletic  training,  track,  basketball,  horseback,  mountain  climbing. 
6  to  10  cigarettes  daily,  not  inhaled.  Education,  high  school,  university  2 
yrs.    Civil  occupation,  civil  engineering.    Unmarried.    Res.,  Ogden,  Tex. 

Physical  examination:  Ht,  66;  wt,  125  (usual  weight);  age,  24.  Pupils 
normal  to  light  and  accommodation.  Tonsils  operated  in  childhood ;  visible 
stumps,  enlarged  cervical  glands.     Knee  jerks  lively.     No  tremor  of  hands. 

Personality  study :  Wears  an  expression  of  slight  apprehension.  Ix)oks  tired, 
a  little  pale,  and  not  fit.  Says  he  turns  in  at  night  at  12  or  2  usually. 
Nearly  fainted  yesterday  while  being  examined    (at  medical  department). 


AIE  SEEVICE   MEDICAL.  341 

fle  seems  direct  and  frank,  but  I  can  not  feel  sure  of  this.  Gives  the 
impression  of  being  mentally  and  physically  tired.  Should  be  seen  again 
and  certainly  not  to  fly  at  present.  He  realizes  he  is  not  in  best  of  condition. 
Can  not  say  positively  there  is  any  psychic  evidence  of  his  lack  of  condition. 
May  be  due  to  tonsils. 
Rating:  Personality,  "E"  (temporarily  on  account  of  tonsils  and  fainting). 

Peesonauty  Recobd. — No.  193. 

Black  Field,  Date . 

J.,  H.  Q.,  1st  It.,  ASSRC,  pilot 

Aviation  history :  Ground  school  July  1st,  1917,  to  Oct.  1,  1917 ;  transf.  to  Black 
Field  to  May  30, 1918.    315  hrs.  flying  to  date.    No  crashes. 

Personal  history :  Typhoid  at  13  yrs.  Fractured  right  humerus  near  shoulder 
joint,  10  years  ago.  Athletic  training,  foot  and  base  ball,  swimming,  tennis ; 
always  in  training.  Education,  4  yrs.  high  school,  3  yrs.  college.  Unmarried. 
Res.,  Philadelphia,  Pa. 

Physical  examination:  Ht.  70;  wt,  154;  pulse  64,  high  tension;  pupils,  equal 
active,  slight  secondary  dilatation ;  knee  jerks ;  active,  easily  exhausted. 

Personality  study :  Has  been  flying  constantly  since  last  year ;  has  felt  feeling 
of  staleness ;  "  loss  of  pep  "  for  1  month.  No  worries  or  fears,  merely  the 
wearing  of  the  steady  grind,  no  variety;  at  present  only  formation  work. 
Quick,  accurate  responses.  Wants  change;  rest  for  a  week  or  two.  Should 
be  watched  during  convalescence  period.  Optimistic  as  to  future.  Increased 
motor  activity;  sweating  localized;  face  flushes  easily.  Has  dreamed  of 
flights  only  recently ;  of  being  in  tail  spin. 

Rating :  Pensonality,  "  E." 

Peesonauty  Recobd. — ^No.  204. 


Field, 


P.  J.,  1st  lieut,  pilot. 


Aviation  history:  May,  1917,  Tech  School,  X  Field — to  date.    70  hrs.  flying  to 

date.    No  crashes. 
Personal  history :  Measles,  pneumonia,  and  recurring  tonsillitis  until  this  year. 

Broken  leg  2  yrs.  ago.     Father  living  and  well,   1  sister  living  and  well. 

Family  firmly  opposed  to  flying.     Wife  greatly  depressed  over  aviation,    2 

small  children.    Married.    Res.,  New  York,  N.  Y. 
Physical  examination :  Ht.,  68 ;  wt.,  165 ;  age,  25.     Knee  jerks ;  very  active. 

Pupils  react  normally  to  light  and  accommodation.     Slight  secondary  dilata- 
tion after  primary  dilatation,  after  primary  contraction. 
Personality  study :  An  excellent  type ;  open  frank,  genuine  forceful,  courageous. 

Has  personal  worries  and  has  good  cause  for  them. 
Rating :  Personality :  "  E." 

Personality  Record. — No.  189. 

E.  Field,  June  29,  1918. 

S.  E.  J.,  2nd  lieut.,  pilot. 

Aviation  history :  Ground  school  July  17-Jan.  18,  1918.    O.  Field,  Feb.  6,  '18-May 
30,  '18.    M.  Field,  to  date.    310  hrs.  flying  to  date.    No  accidents. 


342  AIR  SEEVTCE   MEDICAL. 

I'ersonal  history:  ^Measles  and  malaria  during  ohikibooii ;  tjplioid  at  15,  pneu- 
monia 16.  Athletic  training,  football,  basket  ball,  :ir.d  track.  Education, 
high  school,  2  yrs.  college.  In  Army  since  1915.  No  leave..  Tobacco,  15 
cigarettes  daily.  Alcohol,  moderate.  Family,  father  a!id  mother  living  and 
well;  3  brothers  living  and  well.  No  opposition.  Uiunari'ied.  Res.,  Rock 
Hill,  Ark. 

Physical  examination:  Ht.,  71;  wt.,  174;  age,  23.  Can't  relax  so  it  is  difficult 
to  obtain  knee  jerks  unless  attention  is  diverted  Pupils  active.  Marked 
secondary  dilatation. 

Peronality  study :  Feels  stale  and  shows  some  emotional  instability.  Says  he 
has  not  had  an  acL-idont,  but  knows  one  is  coming.  Probably  does  not  take 
very  good  care  of  himself.  Is  unsafe  for  flying  on  account  of  present  condi- 
tion.    Should  have  vacation. 

Rating :  Personality  :  "  D." 

VIIL— THE  REBREATHIKG  MACHINE. 

The  rebreathing  machine  in  its  simplest  form  consists  of  a  bag 
filled  with  air,  connected  by  a  tube  to  one  side  of  an  absorbing  can 
containing  caustic  soda  (see  fig.  1).  A  tube  leads  from  the  other 
side  /of  the  can  to  a  mouthpiece.  A  clip  having  been  placed  on  the 
subject's  nose  and  the  mouthpiece  in  his  mouth,  he  breathes  into  and 
out  of  the  bag,  the  air  passing  through  the  caustic  soda,  which  re- 
moves from  it  all  of  the  exhaled  carbon  dioxide.  Inasmuch  as  a  part 
of  the  oxj'gen  contained  in  each  breath  is  absorbed  by  the  body  and 
the  carbon  dioxide  is  removed  by  the  caustic  soda,  the  i  olume  of  air 
in  the  bag  gradually  decreases  and  the  percentage  of  oxygen  in  the 
mixture  grows  progressively  less.  Stailing  with  60  liters  of  air  in 
the  bag,  the  average  subject  will  reduce  the  oxygen  to  7  per  cent  in 
about  30  minutes. 

SIMPLE    FORM    OF    REBREATiriNG    APPARATUS. 

The  rebreathing  machines  in  use  in  the  laboratories  of  the  Medical 
Research  Board  embody  the  same  principle  as  the  simple  apparatus 
shown  above,  but  they  are  built  of  metal  and  are  designed  particu- 


mwiwrn 


mm 


I. 


I 

7  J^b sorbin Q  cczn. 

SIMPLE  FORM  OF  REBREATHING  APPARATUS. 

larly  for  the  routine  testing  work  of  the  board.  There  are  at  present 
three  forms  of  the  machine  in  use,  called  respectively  type  A 
(serial  Nos.  2-13,  inclusive),  type  B  (serial  Nos.  14r-22,  inclusive), 


THE    REBP.EATHEK. 


213 


\ 


AIR  SERVICE    MEDICAL.  343 

and  type  C  (serial  Nos.  23-37,  inclusive),  but  they  differ  only  in 
details  and  a  description  of  one  will  serve  for  all  (see  fig.  2).  The 
base  of  the  machine  is  a  steel  tank  (T)  of  60  or  80  liters  capacity, 
according  to  the  type.  Tj^pe  A  has  80-liter,  and  types  B  and  C 
<)0-liter  tanks.  Air  is  inspired  from  the  tank  through  the  pipe  at  the 
left,  and  is  expired  back  into  the  tank  through  the  pipe  and  ab- 
sorbing cartridge  (A)  at  the  right.  The  valves  (VV)  keep  the 
air  stream  flowing  always  in  the  proper  direction.  In  order  to 
inaintain  the  contained  air  at  approximately  atmospheric  pressure 
and  to  allow  for  changes  in  volume,  a  wet  spirometer  (S),  carefully 
counterbalanced,  is  mounted  on  the  tank  and  communicates  freely 
with  its  interior  through  the  vertical  pipe  (P).  A  stylus  attached  to 
the  counterweight  records  the  movements  of  the  spirometer  upon  the 
smoked  drum  of  the  kymograph  (K).  Water  is  admitted  to  the  tank 
through  valve  (E)  to  replace  the  volume  of  the  used  ox3^gen  and  also 
to  flush  out  the  tank  after  an  experiment.  The  water  is  drained  away 
to  the  sewer  b}'  means  of  valve  (F).  Valve  (C)  affords  a  free  open- 
ing to  the  atmosphere  for  flushing  the  tank  of  the  rebreathed  air. 
Valve  (D)  should  invariably  be  closed  w.hile  flushing  the  tank,  other- 
wise vrater  will  enter  the  absorption  cylinder  (A)  and  ruin  the  car- 
tridge. The  cartridge  is  a  cylindrical  paper  tube  filled  with  solid 
caustic  soda,  cast  in  thin  shells  so  as  to  expose  a  large  surface  to  the 
action  of  the  gas.  It  is  prepared  for  use  in  the  machine  by  punching 
the  ends  full  of  quarter-inch  holes  with  a  pencil.  The  brass  ring  is 
then  inserted  in  the  lower  end  of  the  cartridge,  the  rubber  ring  fitted 
over  the  end,  and  the  whole  inserted  into  the  absorption  cylinder. 
Cartridges  should  never  be  used  without  both  rubber  ring  and  brass 
ring  in  proper  position.  Valve  parts  may  be  removed  from  the  air 
valves  (VV)  by  means  of  the  brass  spanner  wrench,  which,  together 
with  two  new  valve  parts,  is  furnished  with  each  machine.  Counter- 
weight slide  rods  should  be  frequently  greased  with  vaseline  and  the 
pulleys  oiled.  In  setting  up  a  machine  care  should  be  taken  to  level 
it  properlj'^,  so  that  the  inner  can  of  the  spirometer  hangs  freely  in 
the  outer  can  and  does  not  rub  against  the  side. 


"-fe*^ 


IX.— TITE    LOW-PRESSURE    CHAMBER. 

The  low-pressure  chamber  at  the  Mineola  laboratory  is  a  cylin- 
drical steel  tank,  8  feet  in  diameter  and  10  feet  high,  standing  on 
end.  It  is  entered  through  a  full-sized  doorway  in  the  side,  and 
forms  a  commodious  and  comfortable  room  in  which  five  or  six  in- 
vestigators may  conduct  physiological,  psychological,  and  ophthal- 
mological  tests  under  conditions  of  reduced  atmospheric  pressure. 

The  reduction  of  pressure  is  bronght  about  by  means  of  a  motor- 
driven  vacuum  pump  of  10  horsepower,  capable  of  rarefying  the 
atmosphere  within  the  chamber  to   a   barometric  pressure  of   140 


344 


AIE  SERVICE  MEDICAL. 


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AIB  SEEVICE  MEDICAL.  345 

millimeters  of  mercury  (equivalent  to  35,000  feet  above  sea  level) 
in  five  minutes.  This  is  more  than  sufficient  for  any  tests  upon 
human  beings. 

The  pump  withdraws  air  from  the  tank  through  a  3-inch  pipe  at 
the  top;  at  the  same  time  fresh  air  is  admitted  at  the  bottom,  the 
amount  being  regulated  by  means  of  a  valve.  The  admission  of 
air  in  this  manner  serves  the  double  purpose  of  ventilating  the  cham- 
ber and  of  determining  the  rate  at  which  the  pressure  is  reduced. 
That  is,  if  the  valve  is  wide  open,  pressure  remains  normal;  if  the 
valve  is  closed,  the  pressure  drops  rapidly.  Thus  by  manipulating 
one  valve  any  rate  of  pressure  rise  or  fall  may  be  secured. 

The  inside  of  the  chamber  is  finished  in  a  flat,  neutral  tint  and 
lighted  by  tungsten  "  daylight "  lamps.  Several  windows  of  thick 
glass  allow  experiments  to  be  watched  from  without. 

An  oxj^gen  supply  is  piped  through  the  wall  into  the  chamber  to 
a  distributing  board,  with  an  individual  tube  and  mouthpiece  for 
each  observer.  A  check  valve  in  the  pump  line  prevents  a  material 
drop  of  pressure  within  the  tank  if,  for  any  reason,  the  pump  is 
stopped. 

For  ease  and  efficiency  of  operation  the  control  has  been  cen- 
tralized. Directly  before  the  operator  is  a  small  window  and  a 
telephone,  enabling  him  to  observe  and  communicate  with  those  in- 
side. At  the  left  of  the  window  is  the  mercury  manometer  indicat- 
ing the  barometric  pressure  within  the  tank,  expressed  in  milli- 
meters of  mercury  and  in  feet  above  sea  level.  At  the  operator's 
left  hand  are  the  valves  regulating  the  oxygen  supply;  the  valves 
at  his  right  hand  control  the  flow  of  air,  and  below  them  is  the 
switch  for  the  motor.  The  operator  need  not  leave  his  post  from 
beginning  to  end  of  an  experiment. 

Figure  12  is  a  view  of  the  chamber. 

X.— THE  CLASSIFICATION  EXAMINATION. 

The  test  for  classification  of  aviators  is  an  outgrowth  of  the  re- 
search work  on  the  physiological  effects  of  low  atmospheric  pressure. 
It  was  found  that  there  were  wide  variations  in  the  resistance  to  such 
effects,  and  the  task  was  undertaken  of  determining  which  indi- 
viduals were  most  suitable  for  the  branches  of  work  which  involve 
flying  to  the  higher  altitudes. 

The  method  of  rating  adopted  corresponds  well  with  the  military 
needs  of  the  service.  In  the  first  place  are  the  fighters,  the  pursuit 
pilots,  who  commonly  fly  about  15,000  feet,  often  above  20,000  feet. 
In  the  second,  the  bombers,  who  fly  comparatively  high  but  rarely 
above  15,000  feet.  Third,  the  observation  planes  keep  mostly  in  the 
lower  levels,  rarely  going  above  8,000  or  10,000  feet.    The  results  of 


346  AIR  SERVICE   MEDICAL. 

the  low-oxygen  test  are  expressed  in  ratings  A,  B,  and  C,  correspond- 
ing to  the  above  requirements.  Class  D  includes  men  who  for  one 
reason  or  another  ought  not  to  fly  at  all;  such  cases  are  occasionally 
found,  though  the  purpose  of  the  test  is  classification  of  flying  per- 
sonnel rather  than  elimination  of  any.  After  several  hundred  tests 
ha^  e  been  made  it  was  found  that  the  number  of  men  passed  in  class 
A  (about  50  per  cent)  was  much  greater  than  the  need  of  the  service 
for  pursuit  pilots.  Since  choice  had  to  be  made  among  these  men 
anyway,  it  was  felt  that  a  still  higher  rating  was  desirable  which 
should  include  the  particularly  hardy  specimens  who  ought  by  all 
means  to  be  chosen  first.  For  this  reason  a  rating  of  AA  is  given 
to  about  10  per  cent  of  men  examined. 

The  examinations  are  being  made  at  the  central  laboratory  at 
Mineola  and  at  a  number  of  the  flving  schools  in  this  countrv.  It  is 
hoped  later  to  send  examining  units  to  every  flying  field  here  and 
abroad,  and  also  to  m.ake  the  examinations  at  an  earlier  period  in  the 
career  of  the  flier  by  installing  examining  units  at  ground  schools  or 
other  concentration  points  for  candidates. 

The  examining  unit  consists  of  four  officers  and  six  enlisted  men. 
The  officers  are  a  ph^^siologist  who  has  general  charge  of  the  conduct 
of  the  test  and  sees  that  the  technical  details  are  carried  out;  a 
clinician  who  passes  on  the  general  physical  fitness  of  the  subject 
both  before  and  during  the  test,  especially  on  the  reaction  of  the 
heart  and  circulation;  a  psychologist  who  determines  the  effects  on 
general  efficiency  as  expressed  by  the  appiaratus  work:  and  an 
ophthalmologist  who  makes  a  careful  preliminary  examination  of  the 
eyes  and  determines  an}''  effects  of  low  oxygen  upon  the  vision.  The 
enlisted  men  manage  the  rebreathing  machine,  make  air  analyses, 
record  pulse  and  blood  pressure  during  the  test,  and  do  the  clerical 
work  on  the  reports. 

The  routine  test  is  carried  out  as  follows:  A  careful  history  is 
recorded  and  a  general  physical  examination  made,  special  attention 
being  given  to  the  circulatory  apparatus.  The  reaction  of  pulse  and 
blood  pressure  is  measured  when  reclining  and  standing,  after  stand- 
ard exercise  (stepping  up  five  times  upon  a  chair),  and  two  minutes 
after  exercise.  It  is  hoped  that  these  simple  tests  will  be  found  use- 
ful when  repeated  later  in  the  career  of  the  flier  to  determine  whether 
he  has  rem.ained  in  good  condition.  It  may  be  stated  that  a  normal 
behaAaor  in  these  reactions  has  been  found  to  be  a  A-ery  fair  index  of 
the  subject's  ability  to  pass  the  low-oxygen  test.  A  careful  examina- 
tion is  now  made  of  the  eyes. 

The  next  step  is  the  rebreathing  test  itself.  The  evidence  is  suffi- 
cient that  this  test  is  a  perfectly  reliable  index  of  tolerance  to  low 
fitmospheric  pressure,  and  the  low-pressure  chamber  has  been  used 


AIR  SERVICE   MEDICAL.  347 

not  as  a  routine  method  of  examination  but  only  as  a  means  of  check- 
ing up  the  results  of  the  other  test  and  for  scientific  purposes. 

The  rebreathing  machine  is  so  adjusted  that  the  average  run  ^v^ll 
be  between  25  and  30  minutes.  During  the  run  the  subject  does  the 
psychological  work  as  described  elsewhere  and  is  carefully  observed 
by  the  psychologist  to  determine  the  earliest  effects  on  attention  and 
motor  coordination,  as  well  as  the  time  of  appearance  of  more  marked 
effects  and  of  total  breakdown. 

Every  three  minutes  the  capacity  of  the  external  and  internal 
ocular  muscles  is  retested  during  the  run  (near  point  of  convergence 
and  near  point  of  accommodation).  During  the  whole  test  the  pulse 
and  blood  pressure,  systolic  and  diastolic,  are  measured  every  one  or 
two  minutes.  The  clinician  keeps  close  watch  of  these  figures  and 
makes  frequent  examinations  of  the  heart.  The  respiration  is  re- 
corded during  the  test  on  a  kymograph. 

The  test  ends  when  the  psychologist  has  detennined  that  the  sub- 
ject has  reached  the  point  of  complete  inefficiency,  or  when  the  clin- 
ician finds  that  the  condition  of  the  circulation  makes  prolongation 
of  the  test  undesirable.  The  latter  contingency  usually  means  either 
that  the  heart  is  abnormal  or  that  fainting  is  about  to  occur  unless 
the  test  is  stopped.  At  the  close  of  the  run  the  air  remaining  in  the 
apparatus  is  analyzed  to  determine  the  oxygen  percentage  reached, 
which  can  be  translated  roughly  into  terms  of  altitude.  A  few  sub- 
jects have  exhausted  the  oxygen  to  6  per  cent  or  a  little  lower;  7  per 
cent  is- a  frequent  figure,  while  poor  subjects  either  become  inefficient 
or  faint  at  considerably  higher  percentages. 

The  results  of  the  test  are  summarized  in  a  plot  of  which  the  ab- 
scissa line  represents  minutes  of  time,  and  the  ordinates  are  per  cent 
of  oxygen,  and  figures  representing  pulse,  blood  pressure,  volume  of 
respiration,  millimeters  of  near  point  of  convergence,  etc.  The  ap- 
pearance of  different  degrees  of  inefficiency  by  the  psychological 
tests  is  indicated  by  symbols  placed  at  the  proper  time  on  the  ab- 
scissa line.  It  is  assumed  (with  reasonable  correctness)  that  a 
straight  line  connecting  the  oxygen  per  cent  at  beginning  and  end  will 
represent  the  per  cent  at  all  intervening  times.  The  basis  of  judg- 
ment on  the  success  of  the  subject  is  the  oxygen  percentage  at  which 
various  phenomena  occur,  and  this  is  reckoned  from  the  height  of  the 
oxygen  line  at  the  time  in  question. 

The  decision  as  to  rating  the  subject  is  made  by  consensus  of  opin- 
ion on  the  basis  of  the  ratings  made  by  each  separate  department  and 
is  ordinarily  the  lowest  rating  assigned  by  any  one  of  them.  No  man 
is  passed  in  class  A  who  has  any  considerable  disqualification  from 
any  point  of  view.  For  example,  a  deficiency  in  vision  whether  ordi- 
narily present  or  only  developing  as  the  result  of  the  test  would  dis- 


348  AIE  SEKVICE   MEDICAL. 

qualify  for  combat  work  no  matter  how  well  the  candidate  performs 
otherwise. ,_ 

Aside  from  ocular  deficiencies  or  general  physical  conditions  of  a 
distinctly  abnormal  nature,  the  rating  of  a  subject  depends  on  the 
answer  to  two  questions.  How  well  does  he  adapt  himself  to  the 
unusual  environment,  i.  e.,  how  well  does  he  preserve  his  efficiency  at 
altitudes  (as  expressed  by  the  psychological  tests)  and*,  second,  at  the 
expense  of  how  much  strain  on  his  circulatory  system  does  he  do  it? 
Many  subjects  will  compensate  admirably,  preserving  their  efficiency 
to  a  very  high  altitude,  but  only  by  means  of  a  very  high  blood 
pressure,  high  pulse,  or  violent  vasomotor  reactions  such  as  would 
lead  us  to  expect  that  this  man  would  wear  out  quickly  in  service  or, 
perhaps,  actually  have  a  circulatory  collapse  in  the  air  and  faint. 

As  to  the  first  question,  that  of  general  condition  and  the  proper 
functioning  of  the  compensatory  apparatus,  our  most  delicate  cri- 
terion is  the  performance  on  this  psychological  test.  If  a  man  is 
able  to  keep  his  brain  clear,  he  is  certainly  compensating  against  low- 
oxygen  effects,  for  the  brain  is  not  only  the  most  important  tissue  to 
protect,  but  it  is  also  the  most  sensitive  to  defective  nutrition.  After 
much  experimentation  with  different  systems  of  rating  a  fairly  em- 
pirical method  of  computation  has  been  adopted  (fully  described 
elsewhere)  which  takes  into  account  the  percentage  of  oxygen  at 
which  various  effects  appear  and  the  duration  of  the  test,  since  longer 
exposure  to  moderate  oxygen  deficiency  may  produce  more  profound 
effects  than  a  short  exposure  to  a  high  degree.  The  rating  is  based 
both  on  the  early  slight  signs  of  abnormal  effect  and  on  the  more 
pronounced  manifestations  up  to  complete  inefficiency.  One  man  may 
be  moderately  inefficient  from  8,000  feet  up,  but  only  break  com- 
pletely at  25,000  feet.  Another  may  remain  perfectly  clear  until 
20,000  feet  and  then  suffer  a  complete  loss ;  probably  the  second  man 
would  be  a  more  useful  flier  than  the  first. 

The  second  question,  that  of  the  amount  of  circulatory  strain 
involved  in  preserving  compensation,  is  answered  largely  by  the 
behavior  of  pulse  and  blood  pressure  and  by  the  sound  of  the  heart 
during  the  test. 

A  fuller  discussion  will  be  found  elsewhere  of  the  method  of  rating 
based  on  circulatory  effect.  A  subject  who  has  a  definitely  diseased 
heart,  no  matter  how  well  compensated,  is  put  in  class  D,  and  it  is 
recommended  that  he  be  kept  ^t  ground  work.  No  man  is  passed 
in  class  A  whose  blood  pressure  is  so  high  that  the  heart  will  be 
continually  undergoing  severe  strain.  Signs  of  circulatory  exhaus- 
tion or  fainting  are  causes  for  rating  in  class  B  or  C. 

It  should  be  stated  that  some  of  these  circulatory  reactions  are 
signs  not  of  constitutional  inferiority  but  of  temporary  lack  of  con- 
dition.   They  none  the  less  give  a  clear  index  of  how  the  man  may 


AIB  SEEVICE   MEDICAL. 


349 


be  expected  to  behave  in  the  air,  and  such  a  temporary  rating  should 
be  followed  until  a  better  general  condition  can  bfe  demonstrated.  It 
is  hoped  that  it  will  be  possible  to  apply  the  test  at  rather  frequent 
intervals  to  the  aviators  in  service  and  thus  determine  whether  they 
are  remaining  in  good  condition  or  becoming  "  stale."  For  this  reason 
it  has  been  arranged  that  the  report  of  the  examination  is  to  accom- 
pany the  aviator  wherever  he  goes  and  be  accessible  to  the  Flight 
Commander  and  the  Flight  Surgeon. 

An  analysis  has  been  made  of  the  results  of  374  routine  examina- 
•tions.    The  results  are  given  in  the  tables  below. 

The  first  table  shows  the  percentages  of  the  various  ratings  among 
various  classes  of  subjects  examined.  Pilots  and  cadets  show  almost 
identical  figures  for  the  higher  ratings,  but  more  absolute  disquali- 
fications were  recommended  among  the  latter.  Nonfliers  make  a 
considerably  poorer  showing. 


Table  No.  1. — Analysis  of  374  examinations. 

AA 

A 

B 

C 

D 

Num- 
ber. 

Per 
cent. 

Num- 
ber. 

Per 
cent. 

Num- 
ber. 

Per 
cent. 

Num- 
ber. 

Per 

cent. 

Num- 
ber. 

Per 
cent. 

TotaL 

Pilots  

15 

16 

9.4 
9.7 

52 
54 

32.7 
32.7 

58 
58 

36.5 
35.1 

32 
27 

20.1 
16.4 

,§ 

1.3 
6.1 

159 
165 

Cadets 

Total  fliers 

Observers 

31 
1 

1 

9.5 
4.3 
3.7 

106 
5 
7 

32.7 
21.7 
25.9 

116 
6 
7 

35.9 
26.1 
25.9 

59 

10 

7 

18.2 
43.5 
25.9 

12 
1 
6 

3.7 
4.3 

18.5 

324 
23 
27 

Others 

Total 

33 

8.8 

118 

31.7 

129 

34.6 

76 

20.3 

18 

4.8 

374 

The  average  age  of  the  various  classes  is  interesting.    This  was 
tabulated  for  193  cases  passed  above  D. 


Table  No.  2. 


Number. 

Age. 

Class  AA 

22 
61 
69 
41 

Yr$.  Mm. 

23  9 
25           1 
25           1 

24  7 

Class  A '  *" 

Class  B '." 

Class  C 

Among  109  cases  of  fliers  rated  class  B  the  reason  for  not  giving  A 
was  as  follows: 


circulatory  exhaustion 
Psychic  deterioration.. 

Both  of  above 

High  blood- pressure... 

Total 


100.0 


350  AIR    SERVICE   MEDICAL. 

Among  65  cases  of  fliers  rated  C  the  reason  therefor  was : 


. 

Number. 

Per  cent. 

Circulatory  exhaustion 

31 

23 

3 

5 

3 

47.7 

Psvchie  deterioration 

35.4 

Both  of  above 

4.6 

High  blood-Dressure 

7.7 

Defective  vision 

4.6 

65 

100.0 

Of  18  men  rated  in  class  D  the  causes  were : 

Valvular  heart  disease 9 

Ventricular   extra  systoles 3 

Deficiency  of  vision  or  ocular  muscles 3 

Color  blindness 1 

Vertigo  of  unknown  cause 1 

Neurotic  constitution,  poor  vasomotor  tone 1 

Total ^ 18 

XL— DIRECTIONS  FOR  THE   CLASSIFICATION   EXAMINATION. 

ROUTINE  FOR  EXAMINATIONS. 

1.  Each  unit  will  consist  of  four  officers  and  six  enlisted  men,  viz : 

1.  Physiologist. 

2.  Clinician. 

3.  Ophthalmologist. 

4.  Psychologist. 

Enlisted  men,  A,  B,  C,  D,  E,  and  F. 

2.  The  ranking  officer  of  each  unit  will  exercise  military  command 
and  v>nll  coordinate  and  expedite  the  work  of  the  unit.  He  will  not, 
however,  usurp  the  right  of  other  officers  to  decide  matters,  especially 
such  as  involve  rating,  Avhich  lie  in  their  own  departments.  Tech- 
nical or  scientific  matters  or  such  as  involve  general  policy  will  be 
referred  to  the  Mineola  Laboratory  through  the  chiefs  of  the 
respective  departments. 

3.  The  routine  test  for  aviators  will  consist  of  (a)  preliminary  test 
by  clinician  and  physiologist  including  history,  (h)  preliminary  test 
by  ophthalmologist,  (c)  test  on  the  rebreathing  apparatus  dur- 
ing which  the  subject's  performance  and  condition  are  observed 
by  clinician,  ophthalmologist,  and  psychologist.  Technical  details  of 
the  test  are  the  responsibility  of  the  physiologist  who  supervises  the 
work  of  the  enlisted  men  on  the  machine  and  in  taking  pulse  and 
blood  pressure.    He  will  not  examine  the  subject  during  the  test. 

4.  The  test  Avill  normally  be  continued  until  the  subject  has  arrived 
at  a  point  where  he  clearly  shows  low  oxygen  effects  or  his  efficienc}' 
as  determined  by  the  psychologist,  and  when  this  point  is  reached, 
the  experiment  will  be  terminated.     In  case,  however,  his  general 


AIR  SERVICE   MEDICAL.  361 

condition  demands  it,  the  subject  should  be  removed  before  this  time. 
The  necessity  for  interrupting  the  test  before  its  natural  termination 
is  to  be  decided  by  the  clinician  though  all  others  present  should 
call  his  attention  to  unfavorable  indications.  This  applies  especially 
to  the  physiologist  and  the  enlisted  man  taking  pulse  and  blood 
pressure,  who  should  promptly  report  to  the  clinician  any  note- 
worthy change  in  these  observations  or  in  the  respiration. 

5.  No  test  should  be  prolonged  beyond  the  point  where  the  final 
rating  can  be  determined.  For  example  if  the  subject's  heart  puts 
him  in  class  C  or  D,  it  is  a  matter  of  no  great  interest  whether  he 
ranks  A  or  B  on  the  psychological  test.  It  is  important  that  the 
test  be  so  conducted  that  subjects  will  not  have  the  expectation  in 
advance  of  undergoing  anything  dangerous  or  disagreeable ;  for  this 
reason  tests  should  rarely  be  prolonged  to  the  point  of  fainting,  un- 
consciousness, or  great  discomfort. 

6.  All  members  of  the  unit  must  exercise  diligent  care  to  prevent 
the  prejudicing,  alarming,  or  exciting  of  the  subject.  This  applies 
not  only  to  subjects  being  tested,  but  to  all  fliers  and  candidates  who 
may  be  later  subject  to  test.  Even  chance  remarks,  which  might 
give  the  impression  that  there  is  danger  or  discomfort  in  the  test, 
or  that  many  men  are  disqualified  as  a  result  of  the  test,  must  be 
scrupulously  avoided.  Unfortunate  remarks  which  seem  unim- 
portant to  the  person  making  them,  do  in  many  cases  produce  such 
an  effect  on  the  subject  that  his  performance  on  the  test  is  materially 
modified. 

7.  Instructions  to  the  aviator  concerning  the  operation  of  the 
psychological  apparatus,  will  be  given  by  the  psychologist  only. 
Additions  by  other  members  of  the  group  are  detrimental. 

8.  During  the  first  three  minutes  of  the  run,  the  aviator  will  be 
coached  by  the  psychologist. 

9.  Stop-watches  of  the  psychologists,  ophthalmologist,  and  car- 
diac observer  will  be  started  simultaneously,  and  all  records  will  be 
kept  in  terms  of  elapsed  time  after  watches  are  started. 

10.  Beginning  at  the  sixth  minute,  and  at  three-minute  intervals 
thereafter,  the  psychological  work  will  be  stopped  for  30  seconds, 
to  allow  the  ophthalmolog;cal  and  cardiac  examination.  It  is  im- 
portant that  the  ophthalmologist  keep  track  of  the  time  so  that  he 
shall  be  ready  promptly, 

11.  Full  instructions  as  to  the  ophthalmological  tests  must  be 
given  previous  to  the  commencing  of  the  run,  so  that  no  instructions 
will  be  necessary  in  the  30-second  period. 

12.  In  case  the  clinician  feels  that  the  subject's  physical  condition 
demands  more  frequent  examinations  these  shall  be  made  in  such 
a  wa.y  as  to  disturb  the  psychological  test  as  little  as  possible. 


352  AIE  SEEVICE  MEDICAL. 

13.  Eebreathing  tests  may  b©  mad©  separately  for  the  purposes 
of  the  different  departments,  but  in  rating  fliers  a  single  test  will 
be  made  as  a  routine.  If  it  seems  desirable  an  unsatisfactory  test 
may  be  repeated. 

14.  Results  should  not  be  indicated  to  the  aviator  except  in  the 
most  general  form — especially  to  be  avoided  is  any  statement  of 
"  how  far  he  went "  in  terms  of  thousands  of  feet  altitude.  It  maj'^ 
be  made  plain  there  is  no  direct  parallel  between  oxygen  percentage 
in  the  rebreathing  test  and  low  atmospheric  pressure,  and  that  in 
the  rapid  progression  of  the  test  the  results  would  be  very  fallacious 
if  applied  to  active  working  conditions  at  high  altitudes. 

15.  The  duties  of  the  officers  are : 

(a)  The  physiologist  will  have  immediate  charge  of  enlisted  men 
A  and  B,  see  that  their  work  is  being  done  properly,  that  all  appa- 
ratus is  in  order,  and  that  necessary  supplies  are  kept  in  sufficient 
stock.  He  will  take  pulse  and  blood  pressure  before  the  rebreathing 
test  in  the  manner  prescribed  on  page  2  of  the  history.  He  will  pass 
on  the  character  of  the  pulse,  respiration,  and  blood  pressure,  con- 
ferring with  the  clinician  as  to  their  bearing  upon  the  normality 
of  the  circulatory  apparatus.  He  will  enter  this  judgment  on  these 
matters  under  "  summary  "  on  page  2  of  the  history. 

(5)  The  clinician  will  carefully  read  the  history  prepared  by  en- 
listed men  C;  go  into  more  detail  as  to  points  suggested,  especially 
as  to  the  exact  condition  at  time  of  test.  He  will  then  make  a  phys- 
ical examination  and  fill  in  the  entries  on  the  history  form  or  dic- 
tate them.  He  will  be  present  at  each  rebreathing  test,  following 
carefully  the  condition  of  the  subject,  interrupting  the  test  if  he  con- 
siders that  the  subject's  physical  condition  demands  it,  being  the 
one  man  responsible  for  ending  the  experiment.  On  completion  of 
the  test  he  will  enter  on  the  blank  (p.  3)  the  exact  condition  at 
beginning  and  at  close  of  test  (especially  whether  unconscious,  faint- 
ing, etc.),  note  manner  of  recovery,  and  any  other  remarks  as  to 
progress  of  test.  He  will  summarize  on  page  2  the  behavior  of  the 
subject's  general  physical  fitness  both  before  and  during  the  test, 
especially  the  behavior  of  the  heart.  He  will  consult  with  the  phys- 
iologist as  to  respiration,  pulse,  and  blood  pressure. 

(c)  The  ophthalmologist  will  conduct  preliminary  tests,  and  tests 
during  the  rebreathing  experiment.  He  will  base  his  rating  on  the 
results  of  both  tests. 

(d)  The  psychologist  will  observe  the  performance  of  the  subject 
during  the  test.  He  will  plainly  signal  to  the  clinician  when  he  is 
ready  to  terminate  the  experiment,  and  the  clinician  will  ordinarily 
take  the  subject  off  at  this  time.  He  will  base  his  rating  on  both 
the  preliminary  performance  and  on  performance  under  low  oxygen. 

16.  The  duties  of  the  enlisted  men  are  as  follows : 


AIR  SERVICE  MEDICAL.  353 

A  will  have  the  care  of  the  rebreathing  machine  during  the  test 
and  will  be  responsible  that  it  is  kept  in  order.  He  will  make 
analyses  and  record  them  on  the  history  sheet,  page  3. 

B  will  take  and  record  pulse  and  blood-pressures  during  the  test 
and  attach  this  record  to  the  history  sheet.  He  will  fill  in  the  names 
at  the  top  of  page  three  of  the  history.  He  will  be  responsible  that 
all  papers  are  taken  to  be  plotted  as  soon  a^  above  entries  are  made. 

C  will  receive  candidates,  give  them  directions  as  to  procedure, 
take  their  history,  assist  physiologist  and  clinician  in  their  examina- 
tions. He  will  also  assist  E  with  copying  and  keeping  in  order 
the  histories. 

D  will  be  responsible  for  making  three  copies  of  the  charts  in 
each  case. 

E  will  be  clerk,  writing  such  letters,  etc.,  as  may  be  ordered,  and 
being  responsible  that  three  identical  copies  of  each  record  are  pre- 
pared, and  that  they  are  mailed  after  approval  to  their  appropriate 
destinations. 

F  will  have  charge  of  the  psychological  apparatus  and  will  man- 
ipulate the  lights  during  the  test.  He  will  assist  in  the  plotting  and 
copying. 

17.  The  Conunanding  Officer  of  the  unit  may  readjust  the  assign- 
ments of  the  enlisted  men  as  he  deems  wise;  e.  g.,  A  and  B  should  be 
interchangeable,  and  it  may  be  necessary  that  C,  D,  and  E  assist  each 
other  somewhat. 

EOUTINE  FOR   RECORD    KEEPLNG. 

1.  Candidates  will  report  to  enlisted  man  C. 

2.  C  will  enter  candidate's  name  in  the  journal,  take  the  history 
and  attach  to  it  the  check  slip.  The  history  (original  copy)  will  be 
either  written  in  ink  or  typewritten.  The  two  copies  will  be  type- 
written. Entries  by  the  various  departments  are  to  be  made  only 
on  the  original  and  the  original  is  to  be  signed  by  each  officer,  military 
rank  being  added  and  designation  as  "  Physiologist,"  etc. 

3.  Each  step  afterwards  is  to  be  initialed  on  the  check  slip  as  it  is 
made. 

4.  Preliminary  pulse  and  blood  pressures  to  be  taken  by  the  physi- 
ologist. 

5.  Physical  examination  to  be  made  and  entered  (or  dictated)  by 
clinician. 

6.  Preliminary  eye  examination  made  and  entered  by  ophthal- 
mologist. 

7.  History  to  go  to  rebreathing  room  with  the  subject,  to  be  de- 
livered to  B.  B  is  to  be  instructed  that  no  test  is  to  proceed  until  the 
history  is  in  his  hands  and  until  all  procedures  up  to  this  point  are 
checked  on  the  check  slip. 


354     ,  AIE  SERVICE   MEDICAL. 

8.  At  the  close  of  the  test  the  names  of  observers  are  to  be  entered 
by  B ;  anj''  remarks  about  the  test  may  be  entered  by  the  physiologist 
or  the  clinician ;  the  clinician  will  enter  condition  at  beginning  and 
close  of  experiment  and  at  this  time  he  will  usually  enter  his  remarks, 
under  the  summary  on  page  2.  The  air  analyses  will  be  entered  by 
B,  who  obtains  them  from  A,  as  well  as  the  exact  time  of  day  and  the 
duration  of  the  test. 

9.  At  the  close  of  the  test  all  papers  (history,  check  slip,  pulse  tind 
pressure  notes,  duplicate  of  psychologist's  notes,  kymograph  tracing) 
are  pinned  together  and  taken  to  plotting  room  by  B,  and  placed  in 
folder  marked  "  Plotting  room.    To  be  plotted." 

10.  Three  identical  plots  are  made  by  D. 

11.  D  takes  all  papers  to  ophthalmologist's  desk  and  places  them 
in  folder  marked  "  Ophthalmologist.  For  notes  on  histories."  Oph- 
thalmological  data  are  to  be  added  to  chart  and  entries  made  under 
summary  on  page  2. 

12.  Papers  taken  in  turn  to  similar  folders  on  desks  on  psycholo- 
gist, physiologist,  and  clinician,  who  similarly  make  their  additions 
to  chart  and  history. 

13.  Each  department  should  attend  to  this  clerical  work  as  expe- 
ditiously as  possible,  and  see  that  papers  are  forwarded  at  once  to 
the  next  department. 

14.  When  notations  are  complete  all  papers  are  to  be  placed  in 
basket  on  C's  desk  marked  "  Examination  complete.  Plotted.  Notes 
made.    To  be  rated." 

15.  A  conference  of  all  officers  on  rating  is  to  be  lield  at  frequent 
intervals,  preferably  each  day.  The  rating  is  decided  on  concensus 
of  opinion,  being  ordinarily  the  lowest  rating  of  any  department. 
The  subject  is  to  be  assigned  to  one  of  four  classes,  viz:  A  (no  re- 
striction as  tp  altitude),  B  (should  not  fly  above  15,000  feet),  C 
(should  not  liy  above  8,000  feet),  and  D  (should  not  fly  at  all). 
Further  recommendations  of  the  board  in  greater  detail  will  at  this 
time  be  dictated  to  E,  who  will  later  see  that  such  entry  is  made.  It 
is  desired  that  recommendations  be  made  as  explicit  and  detailed  as 
possible,  advising  as  to  the  exact  kind  of  work  the  subject  can  do  best. 

Entries  under  recoinmendations  of  the  board  should  be  made  in 
language  understandable  to  the  laity.  (In  the  rest  of  the  report  this 
is  not  important  since  the  data  is  primarily  for  reference  on  repeat 
examinations  or  for  collation.)  The  definite  figures  established  as 
to  altitude  are  to  be  given  as  above.  It  is  a  good  usage  to  explain 
by  a  phrase  or  so  all  ratings  below  A.  For  instance,  if  the  psychol- 
ogist gives  a  rating  of  B,  the  following  phraseology  may  be  em- 
ployed: "  Class  B  (should  not  fly  above  15,000  feet),  becomes  ineffi- 
cient before  highest  altitudes  are  reached."    In  case  of  heart  strain : 


AIR   SERVICE   MEDICAL.  355 

'•  Class  C  (should  not  fly  above  8,000  feet).  Preserves  his  efficiency 
at  moderate  altitudes  only  at  the  cost  of  severe  heart  strain.  Would 
wear  out  soon  if  used  at  high  altitudes,"  etc. 

16.  Records  to  be  returned  to  basket  marked  "  Rated.  To  be 
copied." 

17.  E  will  see  that  three  copies  are  prepared,  identical,  except  that 
only  the  original  need  be  signed.  He  will  then  return  them  to  basket 
marked  "  Copied.    To  be  inspected."  * 

18.  Reports  will  receive  final  inspection  of  Commanding  Officer 
of  unit,  whereupon  E  will  send  the  original  to  the  Commanding  Offi- 
cer of  the  flying  field,  one  copy  to  office  of  the  Surgeon  General, 
United  States  Army,  and  one  will  be  filed  in  the  Medical  Research 
Laboratory.  (For  the  present  all  three  copies  and  all  other  papers 
will  be  sent  to  the  Medical  Research  Laboratory*  at  Mineola,  where 
they  will  be  inspected  and  distributed  as  above.  When  this  is  done, 
it  will  be  advisable  for  the  unit  to  keep  on  file  duplicates  of  the  origi- 
nal notes.  When  the  original  is  sent  direct  to  the  Commanding  Offi- 
cer of  the  flying  field  and  is  thus  on  file  at  the  field,  the  unit  will  not 
need  duplicates.) 

19.  In  filing  records  in  Medical  Research  Laboratory  each  one  as 
it  arrives  will  be  given  a  serial  number  and  all  papers  marked  with 
this  number  placed  in  a  manila  folder  also  marked  with  name  and 
number,  and  filed  serially.  A  smaller  (3  by  5)  card  will  be  made 
out  for  each  record  and  kept  in  a  smaller  file  in  alphabetical  order. 

20.  In  case  the  examination  has  not  been  completed,  the  records 
will  be  kept  in  basket  marked  "  Examination  incomplete.    To  return." 

21.  When  it  is  evident  that  an  examination  will  never  be  com- 
pleted (e.  g.,  if  aviatqr  is  moved  to  another  station),  the  history  will 
be  filed,  not  with  the  completed  histories,  but  in  a  separate  division 
arranged  alphabetically  marked  "  Incomplete.  Will  not  return."  A 
small  card  (3  by  5)  will  be  made  out  for  such  a  record  and  will  be 
filed  with  the  other  small  cards. 

22.  Incomplete  records  on  which  no  rating  has  been  made  will  not 
be  sent  to  the  Commanding  Officer»at  aviation  field  nor  to  the  Chief 
Surgeon,  but  will  be  kept  by  the  unit  unless  the  aviator  has  been 
transferred  when  they  should  be  sent  to  the  Mineola  Laboratory. 

23.  Any  correspondence  relative  to  an  aviator  is  to  be  filed  with 
the  other  reports  at  Mineola. 

DIRECTIONS    TO    CLINICIAN    AS    TO    CONDUCT    OF    REBREATHING    TEST. 

The  clinician  is  to  be  present  throughout  the  test  and  is  primarily 

responsible  for  the  subject's  condition.     It  will  almost  always  be 

possible  to  keep  sufficiently  accurate  track  of  the  heart  action  by 

listening  during  the  eye  examination  in  order  to  avoid  interference 

89118—19 24 


356  AIE    SERVICE   MEDICAL. 

with  the  psychological  test.  In  case  the  safety  of  the  subject  demands 
it,  however,  he  should  not  hesitate  to  examine  the  heart  more  fre- 
quently, especially  toward  the  close  of  the  test. 

The  clinician  will  be  the  one  to  terminate  the  test  by  removing 
the  mouthpiece  or  nose  clip.  About  four  times  out  of  five  probably 
this  will  be  at  the  instance  of  the  psychologist,  wlijo  will  plainly 
indicate  as  soon  as  his  results  are  satisfactory.  When  this  point  has 
been  reached  the  subject  is  probablj?^  within  a  short  space  of  insensi- 
bility and  the  n^outhpiece  should  be  removed  without  delay. 

The  clinician  may  terminate  the  test  before  the  psychologist  has 
got  his  full  results  if  he  considers  that  safety  demands  it,  but  such 
an  occurrence  should  be  infrequent  if  proper  judgment  is  used,  be- 
cause any  abnormal  circulatory  condition  will  give  an  early  psycho- 
logical effect  and  it  is  usually  safe  to  let  the  test  go  to  this  point. 
An  exception  is  any  case  of  cardiac  arrhythmia  (except  sinus  ar- 
rhythmia), which  increases  during  the  test.  In  this  case  the  experi- 
ment should  be  terminated  very  early  from  the  possibility  of  ven- 
tricular fibrillation. 

When  a  definite  cardiac  lesion  can  be  determined  it  is  unnecessary 
to  prolong  the  test,  for  if  the  clinician's  rating  is  C  or  D  it  is  a  matter 
of  small  importance  whether  the  psychologist's  rating  is  A  or  B. 

The  physiologist  may  suggest  terminating  the  test  if  something  is 
manifestly  wrong,  as  e.  g.,  wdth  the  apparatus. 

The  indications  for  interference  by  the  clinician  are  two:  First, 
that  he  has  determined  a  disqualifying  cardiac  condition;  second, 
that  the  subject  is  on  the  verge  of  fainting.  To  guard  against  this 
latter  the  clinician  should  carefully  watch  the  pulse  and  blood- 
pressure  record  and  should  instruct  the  observer  to  call  his  attention 
at  once  to  any  marked  change.  Blood-pressure  r&adings  every  minute 
are  desirable  tow^ard  the  end  of  the  test.  Subjects  who  have  had  an 
excessive  response  in  pulse  and  blood  pressure,  those  whose  hearts 
are  evidently  working  too  hard  throughout  the  test  should  be  espe- 
cially carefully  watched,  but  even  in  these  cases  it  is  always  safe  to 
allow  the  test  to  go  on  either  until  the  psychologist  is  satisfied  or 
imtil  there  are  definite  signs  of  fainting.  Rapidity  in  pulse  or  mod- 
erate increase  in  blood  pressure  is  not  an  indication  for  stopping 
the  test. 

The  first  sign  of  fainting  will  be  a  sudden  drop  in  diastolic  pres- 
sure, followed  later  by  a  drop  in  systolic  pressure,  then  a  drop  in 
pulse.  It  is  often  possible  to  remove  the  mouthpiece  when  the  dias- 
tolic fall  has  occurred,  but  before  the  other  two.  A  slow  and  steady 
decrease  in  diastolic  pressure  is  to  be  regarded  as  normal  if  not 
excessive,  especially  when  the  systolic  pressure  is  not  increasing,  but 
such  a  steady  decline  frequently  ends  with  a  sudden  fall  and  demands 
careful  watching  from  minute  to  minute. 


AIB  SEEVICE   MEDICAL.  357 

It  is  highly  important  to  avoid  fainting  when  possible  (and  even 
the  cerebral  type  of  unconsciousness),  though  a  certain  number  of 
cases  will  faint  in  spite  of  the  most  careful  watching ;  this  may  occur 
with  great  suddenness,  especially  when  coming  early  in  the  run. 

A  middle  ground  must  be  taken,  giving  the  psychologist  as  much 
opportunity  as  possible  for  his  observations  and  yet  avoiding  dis- 
agreeable terminations  of  the  test.  As  remarked  above,  the  psycholo- 
gist should  terminate  the  test  at  least  four  times  out  of  five. 

DIBECTIONS  FOR  CLINICIAN  AS  TO  RATING. 

When  a  diagnosis  of  valvular  lesion  of  the  heart  can  be  made,  no 
matter  how  well  compensated,  the  subject  should  be  disqualified. 
Rarely  in  the  case  of  a  man  who  has  already  qualified  as  a  pilot  and 
where  the  compensation  is  excellent  and  the  reaction  to  the  test  good, 
he  may  be  passed  in  class  C  with  explicit  directions  that  he  be  Very 
carefully  watched  and  be  withdrawn  later  from  all  air  work  if  he 
gives  any  evidence  of  wearing  badly. 

Subjects  who  have  or  develop  arrhythmia  are  to  be  rejected  (except 
sinus  arrhythmia,  which  is  of  no  importance). 

Subjects  who  show  deterioration  of  heart  sounds  (usually'  due  to 
poor  arteries,  fatty  heart,  or  flabby  heart  muscle)  should  be  rejected, 
or  if  the  deterioration  develops  late  in  the  test,  be  rated  in  class  C. 

In  any  of  the  above  cases  the  experiment  should  not  be  prolonged 
beyond  the  point  where  the  clinician  has  fully  satisfied  himself  of  an 
abnormal  heart. 

The  clinician  will  not  be  called  upon  to  decide  on  cases  who  com- 
pensate poorly,  since  they  will  receive  a  low  rating  from  the  psycholo- 
gist, who  will  demonstrate  failure  of  compensation  long  before  the 
clinician  could.  The  type  of  person,  however,  who  because  of  gen- 
erally poor  constitution  fails  to  compensate  at  all  (no  rise  in  pulse, 
none  in  respiration,  no  change  in  blood  pressure),  should  be  rejected 
rathey  than  given  a  low  rating.  Such  cases,  however,  should  be  very 
rarely  found  in  the  Aviation  Service. 

Of  the  cases  who  compensate  well  (probably  75  per  cent  or 
more  of  the  experiments)  the  rating  should  be  based  on  the  amount  of 
circulatory  strain  involved  in  maintaining  compensation. 

It  is  difficult  to  establish  fixed  rules  in  this  regard  and  much  must 
be  left  to  the  judgment  of  the  examiner.  Those  who  become  uncon- 
scious at  less  than  8  per  cent  oxygen  without  circulatory  failure,  of 
course,  deserve  an  A  rating.  We  have  passed  a  few  subjects  who  had 
a  circulatory  collapse  (either  fainting  outright  or  marked  drop  in 
diastolic  pressure)  at  less  than  8  per  cent.  Those  whose  circulation 
fails  between  8  and  10  per  cent  may  be  rated  B,  and  those  above  10 
per  cent  C.  If  in  doubt,  it  is  safer  to  give  a  lower  rating,  since  more 
fliers  will  be  needed  for  lower  than  for  higher  altitudes,  and  the 


358  AIB   SERVICE   MEDICAL. 

late  effects  of  circulatory  strain  are  always  to  be  considered — i.  e., 
the  early  development  staleness.  Rating  should  be  very  conserva- 
tive in  cases  of  high  blood  pressure.  If  this  is  above  150,  the  rate 
should  be  B ;  if  maintained  above  160,  it  should  be  C,  especially  when 
there  is  evidence  of  circulatory  fatigue.  The  paragraphs  on  blood 
pressure  in  the  directions  to  the  physiologist  should  be  carefully 
foUovfed. 

In  cases  given  a  low  rating  on  account  of  circulatory  strain,  the 
fact  should  be  made  evident  under  "  recommendation  of  the  board  " 
on  the  report.  Some  such  phraseology  as  the  following  may  be 
employed:  "Class  C  (should  not  fly  above  8,000  feet).  Maintains 
his  efficiency  at  moderate  altitudes  only  at  the  cost  of  severe  heart 
strain.    Would  quickly  wear  out  if  used  at  high  altitudes." 

NOTES  ON   THE   DIAGNOSIS   OF  VALVULAR   HEART  DISEASE. 

The  cases  of  valvular  disease  which  the  clinician  of  the  research 
board  will  have  to  decide  will  almost  always  be  difficult  to  diagnose. 
This  is  because  the  candidates  have  been  already  carefully  examined 
and  selected. 

The  rebreathing  test  is  a  very  efficient  aid  to  the  more  usual  methods 
of  examination,  and  it  may  pretty  safely  be  asserted  that  a  man  who 
makes  a  good  run  on  this  apparatus  can  have  no  serious  cardiac 
lesion. 

Overemphasis  must  not  be  placed  upon  single  factors.  This  is 
especially  true  of  murmurs.  Systolic  munnurs  are  extremely  com- 
mon, especially  when  heard  at  the  base,  in  cases  where  there  is  no 
organic  disease.  Eoughnesses  of  the  first  sound  that  suggest  a  slight 
thrill  are  also  not  uncommon. 

A  clear  prolonged  diastolic  murmur  is,  of  course,  almost  certainly 
caused  by  either  aortic  insufficiency  or  mitral  stenosis,  but  even  in 
this  case  a  diagnosis  must  not  be  based  on  the  murmur  alone.  Evi- 
dence of  hypertrophy  and  dilatation,  either  or  both,  should  be  present, 
and  in  mitral  cases  a  pretty  marked  accentuation  of  the  pulmonic 
second  sound.  The  trained  ear  learns  to  judge  from  the  character 
of  the  heart  sounds  rather  than  the  murmurs  whether  there  is  organic 
disease  or  not,  but  it  is  difficult  to  express  in  words  just  what  the 
changes  in  the  heart  sounds  are  which  prove  decisive. 

A  heart  with  an  organic  lesion  seems  to  behave  in  one  of  two  ways 
on  the  low  oxygen  test.  It  may  fail  to  compensate  almost  from  the 
start ;  in  this  case  there  may  be  no  accentuation  of  the  first  sound  nor 
of  the  murmurs,  but  rather  a  deterioration  of  the  sounds  and  a 
shortening  of  the  first  interval.  Such  a  subject  will  probably  become 
inefficient  very  early,  will  get  very  blue,  and  be  extremely  uncom- 
fortable; a  number  have  themselves  removed  the  mouthpiece  saying 


AIR   SERVICE   MEDICAL.  359 

they  felt  that  they  were  suffocating.    This  type  of  reaction,  indicat- 
ing poor  heart  muscle,  will  be  rarely  found  among  aviators. 

Much  the  conmioner  type  of  reaction  is  that  of  excellent  compensa- 
tion or  rather  of  overcompensation.  In  this  the  heart  is  evidently 
on  a  heavy  strain  from  the  start,  the  sounds  loud  and  booming,  the 
apex  impulse  heaving,  second  sounds  accentuated.  Murmurs  are 
sure  to  come  out  mucli  more  clearly.  For  a  reason  which  is  difficult 
lo  understand,  this  type  of  case  usually  runs  a  high  blood  pressure, 
140  to  160,  occasionally  even  to  180.  Psychological  efficiency  is  often 
held  very  well. 

Such  well-compensated  hearts  frequently  hold  out  and  do  their 
work  against  the  odds  up  to  a  very  high  altitude.  When  a  diagnosis 
of  valvular  lesion  is  clear,  however,  it  would  be  unwise  to  prolong 
the  test  to  the  point  of  cardiac  failure,  as  the  latter  would  involve 
much  greater  risk  than  in  the  case  of  the  normal  man. 

Numerous  cases  have  been  observed  where  puzzling  murmurs  have 
been  present  on  preliminary  examination,  which  did  not  become 
stronger  during  the  test,  or  even  disappeared;  in  these  cases  the 
whole  course  of  the  test  was  normal,  there  was  no  evidence  of  cardiac 
incompetence  nor  of  overstrain.  In  such  a  case  the  nuirmur  should 
have  no  weight  at  all  in  assigning  the  final  rate. 

While  we  feel  very  strongly  on  the  danger  of  flying  to  a  man  with 
valvular  disease,  there  is  bound  in  every  case  to  be  bitter  disappoint- 
ment and  dissatisfaction  with  the  ruling  of  the  board.  For  this  rea- 
son great  care  must  be  exercised  in  the  diagnosis  and,  when  possible, 
two  competent  clinicians  should  argue  on  the  matter.  Usually  it  is 
best  to  repeat  the  test  to  be  absolutely  sure. 

Probably  the  chief  source  of  doubt  will  come  from  cases  of  poor 
condition  from  other  causes  (bad  cold,  diarrhea,  etc.)  with  func- 
tional murmurs.  In  some  of  these  cases  an  interval  of  two  weeks 
before  a  retest  will  clear  up  the  confusion.  In  the  other  cases  it  may 
be  necessary  to  have  a  more  thorough  inquiry  into  the  general  con- 
dition at  the  post  hospital  or  even  at  a  base  hospital. 

In  case  of  doubt  it  is  safe  to  err  on  the  side  of  protecting  the  man, 
especially  when  he  is  a  candidate  or  a  cadet.  In  case  of  a  finished 
pilot  he  may  be  passed  in  class  C  when  there  is  a  reasonable  doubt, 
but  the  recommendation  of  the  board  should  contain  explicit  direc- 
tions that  his  heart  must  be  very  carefully  watched,  and  that  he  is 
to  be  withdrawn  from  flying  if  trouble  develops.  The  case  should 
be  called  to  the  attention  of  the  Flight  Surgeon  and  the  man  himself 
should  understand  the  situation  thoroughly — both  his  own  condition 
and  the  danger  of  aviation  to  a  defective  heart. 


360  AIR  SEE  VICE   MEDICAL. 

ROUTINE  EYE  EXAMINATION   DURING  REBREATHING  TEST. 

1.  Instruct  the  candidate  fully  as  to  the  methods  of  procedure  dur- 
ing the  rebreathing  experiment  and  the  signs  that  he  will  make  to 
tell  you  when  his  vision  is  blurred,  when  he  is  diplopic,  etc.  It  is 
well  to  take  time  to  instruct  the  candidate  in  this  way  so  that  valu- 
able time  may  not  be  lost  during  the  experiment,  and  the  psycho- 
logical reaction  disturbed  as  little  as  possible. 

2.  Beginning  of  sixth  minute,  after  start  of  rebreathing  experi- 
ment, note  (a)  convergence  near  point;  (h)  accommodation  near 
point;  (c)  field  of  binocular  fixation. 

3.  Note  convergence,  accommodation,  and  field  of  binocular  fixa- 
tion during  first  30  seconds  of  every  third  minute,  and  vision  every 
6  minutes. 

4.  Make  at  least  one  reading  after  candidate  is  removed  from  ap- 
paratus. •• 

5.  Make  note  of  reason  for  removing  man  from  rebreathing  ap- 
paratus on  face  of  card. 

6.  Note  also  on  face  of  card  whether  man  is  apparently  a  desir- 
able candidate  as  far  as  the  eyes  are  concerned. 

7.  All  records  must  be  in  ink. 

8.  Make  all  notes  on  5  by  8  history  card.  Loose  papers  are  un- 
desirable. 

9.  Make  a  record  of  the  examination  in  the  cross  file  under  head- 
ing "  Tests  and  date." 

10.  As  soon  as  oxygen  percentage  is  recorded,  rate  the  candidate 
under  the  date  in  this  manner,  on  the  back  of  the  5  by  8  card : 

(1)  11  per  cent  (per  cent  of  oxygen  at  which  first  permanent  change  occurs). 

(2)  7  per  cent  (per  cent  of  oxygen  where  the  candidate  is  ocularly  inefficient 
from  any  cause).    Eye  (A). 

Thus:  4-20-18.     (1)  11  per  cent.     (2)  7  per  cent.    Eye  (A). 
N.  B. — Make  notes  of  rating  a,  ft,  c,  or  d  on  card  for  tests  and  dates  after 
man's  name. 

11.  As  soon  as  data  is  complete  to  this  point,  enter  it  on  the  three 
copies  of  the  history  and  make  any  necessary  recommendation,  stat- 
ing why  it  is  made. 

(a)  Under  summary  of  observations  during  low  oxygen  tension 
test,  use  scientific  terms. 

(h)  Under  recommendation  of  board,  use  lay  expressions. 

One  copy  of  the  history  is  sent  to  the  Post  Commander,  one  to  the 
Medical  Research  Laboratory,  Hazelhurst  Field,  Mineola,  L.  I.,  and 
one  to  Air  Service  Division,  Surgeon  General's  Office,  Washington, 
D.  C. 

12.  Make  certain  that  the  5  by  8  card  which  is  retained  in  the 
laboratory  gives  a  complete  statement  of  the  reason  why  a  candidate 
was  rated  a,  b,o^  or  d,  and  what  recommendations  were  made  as  to  his 
final  disposition.  • 


AIR  SEEVICE    MEDICAL.  361 

13.  Keep  4  by  6  cross  file  up  to  date,  following  some  such  scheme : 

Index  (cross  scheme  for  Ophthalmological  Department). 

Card  color  scheme:  (1)  yellow,  (2)  blue,  (3)  salmon,  (4)  white. 
Subindex  under    (a)  Rebreathing. 

(b)  Name  and  date  and  altitude  in  feet  where  break  was  first  shown. 

(1)  Men  who  have  flown.     Fliers.     (1)  PUot.  (a)  Have  flown. 

(2)  Observer.     (6)  Have  not  flown. 

(2)  Acclimated. 

(3)  Men  who  show  break  in  accommodation Accommodation. 

(4)  Men  who  show  break  in  convergence Convergence. 

(5)  Men  who  (do  or  not)  show  break  after  abuse  of  alcohol,  insuf- 

ficient  sleep,  sex  excess,   (a)  Yes.j Dissipation. 

(6)  Muscles Muscles. 

(7)  Men  who  show  no  ocular  break Normal. 

(8)  Break  in  field  of  fixation Fixation. 

(9)  Refractive  errors  (break  or  not),   (a)  Yes.j Refraction. 

(10)  Men  show  break  in  vision,     (a)  Acuity  of] 

(b)  Color        > Vision. 

(c)  Field  of    J 

(11)  Mein  who  (do  or  not)  show  break  after  illness Illness. 

(12)  Men  who  (do  or  not)  show  break  after  typhoid  vaccination. 

(13)  Oxygen  given  during  experiment Oxygen. 

(14)  Stereoscopic  vision Stereoscope. 

(15)  Retinal  sensitiWtv.     (a)  Contrast.    \  t?,^^tx  . 

■       (6)  Treshold.    / Ketina. 

(16)  Tension  (Intraocular) Tension. 

(17)  Men  who  have  had  accidents Accidents. 

^,18)  Men  who  are  stale Staleness. 

ROUTINE  MONTHLY  EXAMINATION  OF  THE  EYE  OF  THE  FLIER  ( SUGGESTED). 

A  record  of  the  completed  609  examination  should  be  kept  with  the 
papers  of  each  flier,  with  the  additional  record  of  the  near  point  of 
convergence  and  muscle  strength  finding. 

1.  Visual  acuity :  If  the  visual  acuity  has  altered,  ophthalmoscopic 
examination  should  be  made  to  determine  the  cause. 

2.  Examination  of  the  eye. 

3.  Muscle  balance,  (a)  If  change  in  findings,  record  muscle 
strength. 

4.  Near  point  of  accommodation. 

5.  Near  point  of  convergence. 

N.  B. — If  alteration  is  found  in  any  of  the  above  findings,  stereo- 
scopic vision  should  be  tested. 

OPHTHALMOLOGICAL  EQUIPSIENT   FOR   BRANCH   LABORATORIES. 

1.  Two  small  millimeter  rules,  15  centimeters  in  length. 

2.  One  Prince  rule.    Illiterate  "  Es  "  as  test  object. 


362 


AIR  SERVICE   MEDICAL. 


3.  One  5-foot  centimeter  rule,  marked  in  millimeters,  and  in  de- 
greees  of  tangents  of  arc. 

4.  One  Hare-Marple  battery -handle  electric  ophthalmoscope. 

5.  Two  dozen  batteries  and  three  extra  lamps  for  the  ophthalmo- 
scope. 

6.  One  stop  watch. 

7.  One  Schweiger  hand  perimeter,  with  two  extra  eyepieces,  one 
for  monocular  use  and  one  for  binocular  use. 

8.  Three  75-watt,  110-volt,  nitrogen  daylight  lamps. 

9.  Two  extension  brackets,  with  two  shades. 

10.  One  set  of  visual  acuity  test  cards.     (Black's,  F.  A.  Hardy  & 

Co.) 

11.  Trial  case  No.  4072,  with  a  multiple  Maddox  rod  and  1^-inch 

lens. 

12.  Trial  frame  No.  4157. 

13.  One  box  square  prisms  No.  4112. 

14.  Jenning's  color-test  No.  1. 

15.  Eeeves's  wedge. 

Per  cent  transmission  and  density  of  average  wedge. 


Millimeters 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

OflDsitv               

0.225 
59.74 

0.466 
34.28 

0.70 
19.84 

0.915 
12.14 

1.14 

7.20 

1.39 
4.06 

1.62 
2.40 

1.86 
1.38 

3. 085 
.83 

2.30 

Per  cent  transmission 

.50 

Millimeters 

55 

60 

65 

70 

75 

80 

85 

90 

95 

100 

Density 

2.57 
.26 

2.785 
.16 

3.0 
.1 

3.28 
.05 

3.485 
.03 

3.72 
.02 

3.945 
.01 

4.18 
.006 

4.42 
.003 

4.65 

Per  cent  transmission 

.001 

16.  Two  retinoscopes,  with  an  18  millimeter  plane  mirror. 

17.  One  36- watt,  110-volt,  frosted  bulb,  Edison  Mazda  lamp. 

18.  One  iris  diaphragm  on  stand  (deZeng). 

19.  Opaque  shades  for  examining  room. 

20.  One  5  by  8  filing  drawer  and  500  No.  1  cards  and  500  No.  2 
cards,  with  alphabetical  index  guides. 

21.  One  4  by  6  filing  drawer,  50  yellow  tabbed  cards,  100  blue 
tabbed  cards,  150  salmon  tabbed  cards,  and  300  plain  white  ruled 
cards. 

22.  Copy  of  per  cent  transmission  and  density  for  average  wedge. 

23.  Copy  of  cross-filing  scheme  for  ophthalmological  records. 

24.  Charts  for  recording  the  field  of  vision,  100. 

25.  Charts  for  recording  field  of  binocular  fixation,  100. 

26.  Jaeger  test  type,  6  sets. 

27.  Eeeves  contrast  sensitivity  test  object. 

28.  One  sterescope  and  2-A,  2-B,  and  2-C  cards. 


AIE   SERVICE   MEDICAL.  363 

The  board  requests  that  a  full  report  of  the  work  of  the  bi-anch 
laboratories  be  made  once  a  month. 

The  ophthalmologists  at  the  branch  laboratories  will  be  expected 
to  do  all  the  research  work  possible,  keeping  the  problem  of  the  stale 
aviator  in  mind  and  examining  men  who  have  had  an  accident  or 
are  having  difficulty  in  flying  or  landing.  A  letter  should  be  sent 
weekly  to  the  central  laboratory  at  Hazelhurst  Field,  Mineola,  L.  I., 
to  the  officer  in  charge  of  the  Ophthalmological  Department,  report- 
ing the  progress  of  the  ophthalmological  work,  giving  details  of 
special  examinations  made  and  any  suggestions  for  improving  the 
work. 

INSTRUCTIONS  TO  THE  PSYCHOLOGIST, 

1.  The  reactor  is  given  the  printed  instruction  sheet,  which  he  is 
instructed  to  read  carefully,  while  care  is  taken  to  avoid  distracting 
his  attention.  During  the  reading  the  psychologist  should  be  ready 
to  explain  any  detail  of  the  apparatus  or  method  in  which  the 
reactor  may  show  interest;  and  after  the  reactor  has  finished,  the 
psychologist  further  explains  the  procedure  and  verballj'  emphasizes 
the  important  points  in  the  instruction. 

2.  As  soon  as  rebreathing  commences,  the  reactor  begins  to  respond 
to  the  three  sets  of  stimuli  as  presented  by  the  apparatus  under  the 
manipulation  of  the  psychologist.  During  the  first  three  minutes  of 
the  test  the  psychologist  shall  coach  the  reactor,  if  necessary,  and 
estimate  his  comprehension  composure  (freedom  from  excitement 
or  nervousness),  entering  these  on  the  record  sheet  then  or  later  as 
good,  fair,  or  poor.  He  should  also  note  the  motor  tendencies  of  the 
reactor,  and  if  these  fall  in  one  or  more  of  the  conventional  cate- 
gories, this  also  should  be  entered. 

In  addition  to  these  general  tendencies,  it  is  important  that  the 
psychologist  take  notice  of  the  specific  tendencies  shown  by  the 
reactor,  and  if  definite  types  of  error  are  shown,  watch  during  the 
succeeding  five  or  six  minutes  for  improvements  in  these  details. 

Normally,  the  test  continues  until  complete  inefficiency  is  reached, 
at  which  point  the  psychologist  must  sharply  notify  the  responsible 
medical  attendant  in  order  that  the  reactor  may  at  once  be  given 
air,  and  so  prevented  from  undergoing  the  collapse  which  would 
ensue  in  a  minute  or  so. 

3.  The  psychologist  will  record  the  typical  change  in  the  reactor's 
behavior,  using  the  symbols  which  are  given  on  the  "  symbol  sheet,'' 
so  that  the  recording  will  interfere  as  little  as  possible  with  the 
observing.  After  the  test  is  ended,  the  entries  on  the  record  sheet 
must  be  at  once  completed. 

4.  Beginning  at  the  sixth  minute,  and  at  three-minute  intervals 
thereafter,  the  psychological  work  will  be  stopped  for  30  seconds  to 


364  AIR   SEEVICE   MEDICAL. 

allow  the  ophthalmological  and  cardiac  examination.  It  is  im- 
portant that  the  ophthalmologist  keep  track  of  the  time  so  that  he 
shall  be  ready  promptly. 

5.  The  psychologist  should  endeavor  tactfully  to  remind  the  re- 
actor as  to  the  general  conditions  of  the  test,  particularly  to  remove 
or  avoid  the  impression  that  the  performance  required  is  very  diffi- 
cult. Especial  pains  should  be  taken  to  restore  the  reactor's  com- 
posure if  he  has  previously  been  stirred  up  by  a  psychoanalytic  or 
other  intimate  personal  inquisition. 

6.  All  members  of  the  unit  must  exercise  caution  that  the  reactor 
shall  overhear  no  remarfe,  serious  or  jocular,  concerning  the  diffi- 
culties, danger,  results,  or  other  features  of  the  test  which  mighl 
excite  him  or  cause  apprehension  or  concern.  Trivial  remarks  fre- 
quently have  a  serious  effect. 

INSTRUCTIONS  TO  THE  PHYSIOLOGIST  AS  TO  THE  REBREATHING  TEST. 

It  is  the  physiologist's  duty  to  provide  dependable  conditions  for  a 
rebreathing  experiment.  All  interpretations  of  data  obtained  and 
the  final  rating  of  a  candidate  require  that  the  oxygen  percentage 
during  and  at  the  end  of  a  test  be  accurately  known.  The  analysis 
of  the  air  in  the  tank  at  the  close  of  a  test  must  be  exact.  In  order 
to  have  reliable  analysis  the  gas  analysis  apparatus  nmst  be  clean  and 
the  samples  of  air  carefully  taken. 

A  perfect  experiment  requires  that  the  rebreathing  machine  be  in 
perfect  order.  Leaks  of  water  and  air  into  and  from  the  machine 
must  be  avoided.  Water  may  be  flowing  into  the  tank  during  an 
experiment  through  the  inlet  valve  either  because  it  is  not  perfectly 
closed  or  is  out  of  repair.  Water  may  be  escaping  through  the  out- 
let valve  for  the  same  reasons.  Leaks  of  air  may  be  due  to  faulty  or 
improperly  closed  valves  or  to  loose-fitting  mouth  parts.  Occasion- 
ally a  candidate  may  be  found  who  sucks  in  air  and  allows  it  to  es- 
cape by  not  keeping  his  lips  closed  around  the  rubber  mouthpiece. 

The  movement  of  air  through  the  rebreathing  machine  must  be 
free  so  that  the  breathing  of  the  candidate  is  not  hampered.  It  is 
necessary  to  test  frequently  the  resistance  offered  by  the  absorption 
cartridge. 

The  physiologist  is  also  responsible  for  the  obtaining  and  the  inter- 
pretations of  all  physiological  data.  These  data  for  the  present  in- 
clude the  frequency  and  volume  of  breathing,  the  pulse  rate,  and  the 
three  arterial  pressures — systolic,  diastolic,  and  pulse. 

The  respiration  data  are  obtained  from  the  Irymograph  record  of 
the  spirometer's  movements.  This  record  is  ahnost  valueless  if  there 
has  been  leakage  of  water  or  air  during  an  experiment.  The  cali- 
brating of  the  spirometer  and  the  drawing  of  the  scale  should  be 


ATE  SERVICE   MEDICAL.  365 

accurate  in  order  that  the  per  minute  volume  of  breathing  may  be 
determined  with  exactness.  From  the  varnished  lq;^mograph  tracing 
the  volume  of  breathing  per  minute  is  calculated  for  as  many  sepa- 
rate minutes  as  will  be  found  necessary  in  order  to  determine  the 
curve  of  respiration  throughout  the  experiment.  The  volume  of 
breathing  should  be  calculated  by  the  physiologist  and  the  amount 
and  the  time  of  each  minute-volume  writtep  down  and  then  handed  to 
the  "  plotter,"  who  will  incorporate  them  in  the  final  record. 

The  so-called  normal  pulse  and  blood  pressures  are  determined 
three  or  four  times  while  subject  sits  at  the  machine  with  nose  clip 
on  and  mouthpiece  in  place.  These  normals  should  be  compared  with 
those  of  the  preliminary  pulse  rate  and  blood-pressure  study.  A 
psychic  influence  should  be  avoided  if  possible.  After  rebreathing 
is  begun  the  pulse  rate  is  counted  every  minute  and  the  arterial  pres- 
sures determined  every  other  minute  until  the  eighteenth  minute,  after 
which  they  are  taken  each  minute  until  the  end  of  the  experiment. 
The  O  space  of  the  record  sheet  should  be  left  blank  and  the  determi- 
nation of  the  first  half  minute  recorded  on  the  line. 

The  rule  to  be  followed  in  making  the  determinations  is  to  count 
the  pulse  rate  in  the  interval  between  20  and  40  seconds  and  to 
record  the  count  on  the  half  minute.  The  first  count,  therefore,  will 
be  recorded  on  the  line  between  0  and  1.  The  systolic  and  diastolic 
pressures  should  be  determined  in  the  interval  between  45  and  15 
seconds  by  the  stop-watch  and  recorded  as  having  been  taken  on 
the  minute.  These  should  be  entered  on  the  record  sheet  in  the  space 
between  the  lines,  the  first  determination  in  space  1.  This  system 
of  recording  will  make  it  possible  for  the  "  plotter "  to  indicate 
the  time  intervals  with  exactness  on  the  chart.  It  is  important  that 
the  exact  time  of  the  termination  of  the  experiment  be  indicated  on 
the  circulation  sheet  so  that  the  man  who  plots  the  record  may 
correctly  indicate  with  a  heavy  line  the  time  the  candidate  was 
taken  off. 

The  physiologist  should  closely  watch  the  respiration  and  circula- 
tion changes  toward  the  end  of  the  test  and  should  inform  the  clin- 
ician when  unfavorable  conditions  develop. 

In  order  that  the  ratings  may  be  just  to  all,  the  volume  of  air 
rebreathed  should  be  large  enough  to  require  30  minutes  to  reduce 
the  oxygen  to  7  per  cent.  To  obtain  uniformity  in  the  rate  of 
oxygen  reduction  the  water  level  in  the  tank  should  be  varied  ac- 
cording to  the  size  of  the  man  to  be  tested.  A  larger  volume  of  air 
is  required  for  a  large  muscular  man  and  a  smaller  volume  than  that 
used  for  the  average  for  a  small  man.  The  physiologist  should  de- 
cide what  level  of  water  in  the  tank  of  the  rebreathing  apparatus 
is  necessary  to  provide  the  requisite  time  for  the  test.     Experience 


366  AIR  SERVICE   MEDICAL. 

will  soon  make  it  possible  to  adjust  the  volume  satisfactorily  ac- 
cording to  the  size  of  the  candidate  to  be  tested. 

Rating. — When  rating  a  candidate  as  to  ph^'^siological  responses, 
take  into  account  the  per  cent  of  oxygen  reached  and  the  time  re- 
quired for  rebreathing.  Ordinarily  a  lower  percentage  will  be 
tolerated  when  the  fall  in  oxygen  is  rapid  and  the  run  short  than 
when  the  fall  in  oxygen  is  slow  and  the  time  long.  If  two  candi- 
dates who  both  endured  down  to  7  per  cent  oxygen,  one  reaching  it 
in  15  and  the  other  in  30  minutes,  are  being  rated  it  would  be  unfair 
to  the  man  who  made  the  longer  run  to  grade  him  on  the  same  basis 
as  that  of  the  short  iim.  This  is  the  reason  for  demanding  that  all 
candidates  be  given  a  sufficient  volume  of  air  for  rebreathing  to 
insure  a  run  of  25  to  30  minutes. 

In  rating  take  into  consideration  also  compensation  in  the  breath- 
ing and  circulation.    The  reaction  of  respiration  will  be  recorded  as 
poor,  fair,  good,  or  excessive.     The  majority  of  the  men  examined* 
have  shown  at  between  8  and  6  per  cent  of  oxygen,  an  increase  of 
5.5  liters  in  the  volume  of  air  breathed. 

Such  an  increase  is  rated  good,  an  increase  of  15  or  more  liters 
is  regarded  as  excessive.  The  respiratory  response  is  most  marked 
after  12.5  per  cent  of  oxygen  has  been  reached.  The  increase  in  the 
frequency  of  the  pulse  rate  for  the  majority  of  men  who  have  reacted 
well  has  varied  between  20  and  40  per  minute  at  about  8  per  cent  of 
oxygen.  An  acceleration  of  more  than  50  may  be  regarded  as  ex- 
cessive. The  degree  of  acceleration  is  ordinarily  slight  until  the 
oxygen  has  fallen  to  between  13  and  9  per  cent,  but  from  these  down 
the  acceleration  occurs  rapidly.  The  rise  in  systolic  pressure  usually 
is  not  more  than  20  millimeters,  a  greater  rise  is  considered  ex- 
cessive. A  diastolic  pressure  fall,  when  it  occurs,  will  be  either  a 
slow  controlled  drop  or  of  the  rapid  fainting  type  which  is  often 
spoken  of  as  a  break  in  the  circulation. 

Candidates  are  rated  AA  if  the  compensations  are  good  down  to 
7  per  cent  or  less  and  A  if  good  to  between  8  and  7  per  cent.  They 
are  rated  B  if  the  compensatory  mechanisms  show  decided  insuffi- 
ciency or  failure  between  10  and  8  per  cent,  and  C  if  the  failure 
occurs  above  10  per  cent  oxygen.  The  physiologist  rarely  finds 
reason  for  placing  a  candidate  in  class  D.  A  high  systolic  pressure, 
150  millimeters  and  above,  throughout  the  greater  part  of  the  test 
disqualifies  the  candidate  for  class  A  no  matter  whether  he  com- 
pensates well  or  not. 

THE    PRELIMINARY    PULSE    AND    BLOOD    PRESSURE    STUDY. 

The  candidate  reclines  for  five  minutes.  The  heart  rate  is  then 
determined    by    counting    the    pulse    rate    by    20-second    intervals. 


AIR  SERVICE   MEDICAL.  367 

Counting  should  continue  until  two  successive  intervals  give  the  same 
result.  The  arterial  pressures  are  then  determined.  The  candidate 
then  stands,  the  heart  rate  is  counted  as  before  until  it  reaches  a  con- 
stant rate,  when  it  is  recorded,  and  the  blood  pressures  then  taken. 

The  candidate  then  raises  himself,  by  placing  his  right  foot  on  a 
chair,  five  times  to  the  standing  position  on  the  chair.  The  pulse 
rate,  with  the  candidate  standing,  is  immediately  counted  and  as 
soon  as  possible  thereafter  the  blood  pressures  are  determined.  The 
candidate  stands  at  ease  for  two  minutes,  after  which  the  pulse  rate 
and  the  blood  pressures  are  again  determined. 

The  purpose  of  these  observations  is  to  determine  whether  the  can- 
didate shows  evidences  of  staleness.  In  the  physically  fit  the  heart 
rate  does  not  increase  much  on  standing,  but  in  the  wearied  or  phys- 
ically stale  it  increases  as  much  as  44  beats  per  minute.  The  vaso- 
motor control  of  the  splanchnic  area  responds  to  changes  in  posture. 
In  the  fit  subject  the  splanchnic  vasotone  increases  and  the  blood 
pressure  is  raised  about  10  millimeters  when  he  moves  from  the  hori- 
zontal to  the  upright  standing  posture.  Weakness  is  shown  by  a 
decrease  in  blood  pressure  and  at  other  times  by  an  excessive  increase 
in  the  heart  rate.  A  great  acceleration  in  the  pulse  rate  following 
the  exercise  is  also  a  result  of  staleness.  The  systolic  pressure  should 
return  to  normal  within  two  minutes.  The  subnormal  pressure,  and 
the  length  of  time  it  continues  after  exercise,  has  been  attributed  to 
lack  of  condition. 

PREPARATION  OF  THE  REBREATHING  MACHINE. 

(1)  Flush  the  tank  to  remove  all  vitiated  air.  Do  this  as  follows: 
Close  the  gate  valve  under  the  COo  absorber,  and  also  the  valve  in  the 
return  pipe.  Open  the  valve  on  the  spirometer  pipe.  Open  the 
inlet  valve  of  the  water  system  and  allow  the  tank  to  fill  slowly. 
When  the  tank  is  full,  raise  and  lower  the  spirometer  drum  several 
times  to  change  the  air  in  its  dead  space. 

(2)  Fill  the  tank  with  new  air  as  follows :  Open  the  gate  valves  in 
the  air  pipes  and  close  the  valve  in  the  spirometer  pipe.  Let  the 
water  drain  entirelj'  out.  Set  the  valves  as  before  and  refill  with 
water  a  second  time.     Let  drain  as  before  to  the  desired  level. 

(3)  Set  the  machine  for  the  start  by  opening  the  valves  in  the  air 
pipes  and  closing  the  valve  in  the  spirometer  pipe. 

(4)  Sterilize  the  mouthpiece  by  bringing  it  to  the  boiling  point. 
See  that  the  corrugated  rubber  hose  is  clean  and  dry. 

PREPARATION    OF  THE   RECORDING   APPARATUS. 

The  excursions  of  the  spirometer  indicate  the  depth  and  rate  of 
breathing  of  the  subject.  A  fishline  connected  to  the  top  of  the 
spirometer  runs  over  a  pulley  and  fastens  to  a  counterbalance  for 


368  AIE  SEEVIOE   MEDICAL. 

the  spirometer  can.  A  writing  point  is  attached  to  the  coun- 
terbalance and  records  the  respiration  on  the  smoked  drum  of  the 
kymograph.  The  writing  point  is  best  cut  from  celluloid  film.  The 
angle  of  the  point  should  not  be  less  than  60  degrees  because  very 
acute  points  twist  easily.  The  point  may  be  attached  to  an  aluminum 
stylus  by  means  of  beeswax. 

A  signal  magnet,  provided  with  a  writing  point  and  connected  in 
series  with  two  cells  and  a  clock  interrupter,  records  equal  intervals  on 
the  revolving  drum — usually  half  minutes. 

SMOKING  THE  DRUM. 

Lay  the  kymograph  paper  on  the  table,  glazed  side  down  and  glued 
end  away.  Hold  the  drum  with  the  top  to  the  right  and  lay  it  across 
the  middle  of  the  paper.  Bring  both  ends  of  the  paper  toward  each 
other,  letting  the  glued  end  overlap.  Glue  it  firmly  to  the  glazed  side 
of  the  unglued  end  so  that  the  paper  is  wrapped  tightly  around  the 
drum. 

Smoke  the  drum  over  a  4-inch  single-burner  oil  stove,  or  a  fish- 
tail gas  burner.  Hold  the  a;sis  of  the  drum  in  each  hand  and  let  the 
drum  revolve  rapidly  toward  you,  moving  the  drum  from  side  to 
side  at  the  same  time.    Smoke  it  only  until  it  is  coated  light  brown. 

Arrange  the  drum  so  that  the  writing  point  attached  to  the  spirom- 
eter and  that  of  the  signal  magnet  will  mark  evenly  on  the  drum. 
The  stylus  of  the  signal  magnet  should  be  about  1  centimeter  above 
the  lower  edge  of  the  drum  and  about  1  centimeter  in  front  of  the 
spirometer  stylus. 

OPERATION  OF  THE  MACHINE. 

Let  the' subject  sit  so  that  the  mouthpiece  can  be  held  comfortably 
in  the  mouth  without  twisting  or  pulling  in  any  direction.  Close  the 
signal  magnet  switch.  Start  the  kymograph.  See  that  the  valves  in 
the  pipes  are  open  and  that  the  gate  valve  in  the  spirometer  pipe  is 
closed.  Put  on  the  nose  clip.  The  physiologist  will  start  the  experi- 
ment by  putting  the  cork  in  the  mouthpiece  at  the  end  of  an  expira- 
tion.   The  stop  watches  should  be  started  at  this  time. 

As  the  experiment  progresses  the  oxygen  from  the  tank  is  used 
up  progressively.  The  spirometer  stylus  will  write  nearer  the  top 
of  the  drum.  Open  the  inlet  valve  in  the  water  system  and  let  a 
little  water  flow  into  the  tank,  sufficient  to  bring  the  writing  point 
nearly  to  the  bottom  of  the  drum.    Eepeat  this  as  often  as  necessary. 

Wlien  the  experiment  is  ended  close  the  valves  in  the  air  pipes 
until  the  air  samples  are  taken. 

Write  the  name  of  the  subject,  date,  and  type  of  experiment  on  the 
smoked  drum.  It  is  also  convenient  to  record  the  oxygen  per  cent. 
Eemove  the  paper  by  cutting  through  the  outer  sheet  at  the  lap. 


AIE  SEBVICE   MEDICAL.  369 

Do  not  cut  through  both  sheets  and  scar  the  drum.  Hold  the  paper 
by  each  end,  smoked  side  up,  and  pass  it  once  through  a  shellac 
solution.    Hang  it  up  to  dry. 

CARE  OF  THE  APPARATUS. 

Leaks. — If  a  leak  is  suspected  from  the  character  of  the  respira- 
tion record,  first  see  that  the  valves  of  the  watei'  system  are  closed. 
A  leak  of  water  into  the  tank  through  the  mlet  valve  will  make  the 
lower  level  of  the  respiration  tracing  approach  the  horizontal.  A 
leak  of  water  out  of  the  tank  through  the  drain  valve  will  make  the 
record  approach  the  perpendicular. 

Leaks  of  air  out  of  the  sj^stem  most  frequently  occur  around  the 
mouthpiece.  It  may  be  necessary  to  tape  the  rubber  portion  to  the 
metal  part.  Leaks  of  air  around  plumbing  joints  may  be  stopped  by 
using  white  lead  or  heavy  paint. 

The  CO 2  ahsorber. — This  is  a  cylindrical  pasteboard  carton  filled 
with  shell  sodium  hydroxide.  This  cartridge  is  contained  in  a  steel 
case  and  is  easily  replaced.  It  is  effective  in  removing  COo  for  about 
200  to  240  minutes  of  rebreathing.  If  the  cartridge  becomes  very 
warm  or  the  subject  breathes  excessively  do  an  analysis  for  COo,  and 
if  it  is  present  reject  the  cartridge.  Before  each  experiment  the 
resistance  of  the  cartridge  to  expired  air  should  be  tried  by  blowing 
through  the  cartridge  with  the  air  valve  below  it  open  and  the  other 
valves  closed.  The  spirometer  can  be  easily  raised  if  the  sodium 
hydrate  is  not  caked. 

When  a  new  cartridge  is  inserted,  punch  both  ends  full  of  holes 
with  a  pencil,  put  the  loose  brass  ring  inside  the  lower  rim  of  the 
pasteboard  cartridge,  put  the  rubber  gasket  around  the  outside  of  the 
lower  rim,  put  the  cartridge  with  the  marked  end  up  into  the  steel 
case  and  tighten  the  thumb  screws.  Do  not  use  a  cartridge  without 
a  brass  ring  and  always  remove  brass  ring  before  rejecting  a  used 
cartridge. 

Shellac. — Make  a  saturated  solution  of  powdered  shellac  and  de- 
natured alcohol  containing  about  1  teaspoonful  of  castor  oil  to  each  2 
quarts  of  alcohol.  The  mixture  should  be  shaken  thoroughly  and  a 
residue  of  undissolved  shellac  should  always  remain  in  the  bottom 
of  the  bottle.  If  the  records  appear  running  after  shellacing,  the 
solution  probably  needs  more  shellac.  Do  not  allow  the  shellac  to 
stand  exposed  to  the  air  except  while  it  is  being  used.  The  castor 
oil  makes  the  dried  record  more  flexible. 

Kymogra'ph. — The  kj^mograph  consists  of  an  aluminum  drum  re- 
volved by  means  of  a  clockwork  at  its  base.  The  drum  slides  on  a 
brass  sleeve  and  is  held  at  any  desired  height  by  a  spring  clip.  The 
sleeve  ends  in  a  friction  plate  which  rests  on  a  metal  disk  driven  bv 
the  clockwork.    The  sleeve  and  friction  plate  revolve  about  a  steel 


370  AIR  SERVICE   MEDICAL. 

shaft  which  passes  through  both  of  the  heavy  plates  containing  the 
clockwork  and  is  bolted  at  the  bottom  plate.  At  the  top  of  the 
sleeve  is  a  screw  bj'^  means  of  which  the  diiim  and  sleeve  may  be 
lowered  until  the  friction  plate  rests  upon  the  metal  disk.  It  is 
always  used  in  this  position  when  driven  by  the  clockwork. 

In  the  clockwork  are  a  pendulum  and  a  ratchet  wheel  which  pro- 
vide for  a  slower  speed  than  can  be  obtained  by  any  of  the  fans. 
It  may  be  thrown  in  gear  by  raising  the  pin  in  the  gear  peg  out  of 
the  hole  in  which  it  rests.  When  the  screw  near  the  fan  pinion  is 
screwed  down  the  clockwork  operates  as  a  medium-spring  kymo- 
graph. When  this  screw  is  up  the  drum  revolves  approximately 
once  an  hour,  which  is  the  speed  used  for  rebreathing  work. 

CALIBRATION  OF  THE  SPIROMETER. 

In  order  that  the  volume  of  air  breathed  during  any  period  may 
be  determined,  the  relation  between  the  definite  volume  of  air 
breathed  and  a  certain  linear  measure  (1  centimeter,  for  example) 
on  the  kymograph  must  be  established. 

To  calibrate  the  spirometer,  remove  the  can  and  fill  it  with  water 
to  a  depth  of  25  centimeters,  measuring  with  a  graduate  the  amount 
of  water  used.  If  a  liter  or  cubic  centimeter  measure  can  not  be 
obtained,  use  a  quart  or  a  pint  measure.  (One  quart  equals  1.36  liters ; 
1  pint  equals  0.568  liter;  1  fluid  ounce  equals  28.66  cubic  centi- 
meters.) Divide  the  volume  in  cubic  centimeters  by  the  depth  of 
the  water  and  the  quotient  will  be  the  volume  contained  in  the  can 
per  centimeter  of  length.  To  make  the  relation  scale,  let  1  centi- 
meter be  equivalent  to  the  volume  determined  above.  This  may 
be  attached  to  the  spirometer  so  that  the  pointer  will  pass  over  the 
scale  on  each  respiration.    Or  it  may  be  used  for  plotting. 

THE  GAS  ANALYZER. 

DESCRIPTION   OF  APPAEATUS. 

The  apparatus  consists  essentially  of  a  25  cubic  centimeter  gas  bu- 
rette with  a  bulb  containing  about  17  cubic  centimeters  and  a  tube  be- 
low graduated  from  18  to  25  cubic  centimeters  in  0.02  cubic  centi- 
meter, so  that  it  can  be  read  easily  to  0.01  cubic  centimeter.  The  lower 
end  of  the  burette  connects  with  a  temperature-control  tube  similar 
to  the  gas  burette,  but  not  graduated,  and  a  leveling  bottle  containing 
1  to  2  per  cent  sulphuric  or  other  acid  in  50  per  cent  alcohol.  The  top 
of  the  burette  communicates  (by  means  of  a  capillary  tube)  with  an 
absorber  for  carbon  dioxide  containing  10  per  cent  sodium  hydroxide, 
and  a  similar  absorber  for  oxygen,  containing  a  solution  of  pyrogai- 
lic  acid  in  nearly  concentrated  potassium  hydroxide. 


AIR    SERVrCK    MEDICAL.  371 

There  are  four  glass  stopcocks  which  must  always  work  freel3\  A 
two-way  stopcock  is  situated  on  a  T  just  above  the  gas  burette  by 
means  of  which  a  sample  may  be  taken  and  a  contaminated  sample 
expelled.  A  one-way  stopcock  is  situated  just  above  the  bulb  of 
the  control  tube  and  should  always  be  kept  closed  during  an  analy- 
sis. A  one-Avay  stopcock  is  situated  above  each  of  the  absorbers 
and  should  ahvays  be  kept  closed  except  when  the  particular  ab- 
sorber is  in  use. 

Around  the  two  bulbs  is  a  jacket  which  is  filled  with  water  at  room 
temperature.  The  water  in  the  jacket  can  be  mixed  by  blowing  air 
through  a  glass  tube  passing  to  the  bottom.  It  is  important  to  keep 
the  water  thoroughly  mixed  in  order  to  insure  the  same  temperature 
and  water-vapor  tension  in  the  gas  burette  and  the  control  tube  at 
the  time  of  an  experiment. 

USE  OF  THE  APPARATUS. 

1.  Before  an  analysis  is  begun  it  must  be  assured  that  the  capillary 
tubes  between  the  gas  burette  and  the  absorbers  contain  nitrogen. 
This  is  the  case  after  an  analysis  for  CO2  and  O,,  and  it  may  be 
necessary  to  do  an  analysis  for  this  purpose. 

2.  At  the  beginning  of  an  analysis  the  level  of  the  sodium  hy- 
droxide and  the  alkaline  pyrogallate  in  the  absorbers  should  be  a  cer- 
tain height  marked  by  a  wire.  The  level  may  be  adjusted  with  all  the 
stopcocks  closed,  except  that  to  the  particular  observer  in  which  the 
level  is  being  adjusted.  The  leveling  bottle  is  carefully  raised  or 
lowered  and  the  stopcocks  closed  when  the  meniscus  of  the  fluid  comes 
to  the  wire,  or  the  wire  may  be  set  to  the  meniscus.  After  an 
absorption  the  level  is  again  adjusted  to  the  wire. 

3.  The  level  of  the  fluid  in  the  control  tube  is  next  adjusted.  A 
strip  of  millimeter  paper  is  pasted  on  the  leveling  bottle.  The  top 
of  the  gas  burette  and  the  control  tube  are  opened  to  the  outside  air. 
The  leveling  bottle  is  lifted  a  short  distance  so  that  the  level  of  the 
fluid  in  the  control  tube  comes  someAvhere  between  24  and  25  on  the 
scale  of  the  gas  burette.  The  level  of  the  fluid  in  the  control  tube 
and  that  in  the  leveling  bottle  should  be  the  same,  and  the  point  is 
marked  by  the  sliding  wire.  The  stopcock  on  the  control  tube  is 
then  closed  and  kept  closed  during  the  remainder  of  the  analysis. 

4.  The  stopcock  at  the  top  of  the  gas  burette  is  open  to  the  outside 
air  and  the  leveling  bottle  is  lifted  until  the  gas  is  expelled  from  the 
burette  and  a  few  drops  of  fluid  run  out.  The  stopcock  is  then  turned 
so  as  to  communicate  with  the  source  of  gas,  and  a  sample  is  then 
taken  by  lowering  the  leveling  bottle.  The  sample  may  be  driven 
back  into  the  collector  several  time  to  insure  a  representative  por- 
tion. The  stopcock  is  closed.  The  time  is  noted  at  which  the  column 
of  fluid  falls  in  the  gas  burette,  and  no  reading  is  taken  until  exactly 
two  minutes  have  elapsed.    This  is  to  insure  proper  drainage  of  fluid 

89118—19 25 


372  AIE  SEBVIOE  MEDICAL. 

from  the  inside  of  the  tube.    If  large  drops  stand  on  the  inside  after 
two  minutes  the  tube  needs  cleaning. 

5.  Before  reading  the  volume  of  the  sample,  or  later,  when  reading 
the  volume  of  the  residual  gas  in  the  burette,  the  leveling  bottle  is 
moved  up  or  down  on  the  control  tube  until  the  level  of  the  liquid 
in  the  control  tube  comes  to  the  wire.  By  means  of  the  millimeter 
paper  strip  note  is  made  of  the  height  above  or  below  the  meniscus 
in  the  control  tube  at  which  the  bottle  must  be  held  to  bring  the  gas 
in  the  control  tube  to  its  original  volume  (at  the  wire).  The  leveling 
bottle  is  then  held  at  the  same  height  above  or  below  the  meniscus  in 
the  burette  and  a  reading  taken.  In  this  way  the  gas  in  the  burette 
can  always  be  brought  to  the  correct  volume  per  molecule. 

6.  The  sample  is  now  driven  into  the  CO2  absorber.  (Samples 
from  the  rebreathing  machine  should  not  contain  COo,  so  this  step 
may  be  omitted  and  the  O,  absorption  carried  out  directl3\)  With 
the  leveling  bottle  above  the  level  of  the  fluid  in  the  burette,  the 
stopcock  above  the  COg  absorber  is  opened  and  the  bottle  lifted  in 
order  to  drive  the  sample  into  the  absorber.  The  gas  is  driven  over 
eight  or  ten  times,  after  which  the  bottle  is  lowered  carefully  until 
the  level  of  the  sodium  kydroxide  in  the  capillary  tube  comes  up  to 
the  wire.  The  stopcock  is  closed.  A  reading  of  the  remaining  vol- 
ume is  taken  in  the  usual  manner  after  two  minutes.  The  difference 
in  volume  divided  by  the  original  volume  and  multiplied  by  100 
gives  the  per  cent  of  CO2  in  the  sample. 

7.  The  oxygen  absorption  is  now  carried  out  in  a  similar  manner, 
the  level  of  the  alkaline  pyrogallate  being  brought  back  to  the  wire 
and  the  stopcock  closed  before  a  reading  of  the  residual  volume  is 
made.  This  volume  subtracted  from  the  volume  remaining  after  the 
CO2  has  been  absorbed  (or  from  the  original  volume  if  the  sample  is 
ordinary  uncontaminated  air)  gives  the  volume  of  O2  in  the  sample, 
which,  when  divided  by  the  original  volume  times  100,  gives  the  per 
cent  of  O2  in  the  sample. 

Example :  Volume  of  sample         24. 00 
After  CO2  absorption  22.  52 


1. 48—  6. 17  per  cent  CO2 
After  O2  absorption      19. 14 

3.  38—14. 08  per  cent  O2. 

SUMMARY  OF  THE  PROCEDURE  FOR  AIR  ANALYSIS. 

1.  Be  sure  that  the  capillary  tube  contains  nitrogen. 

2.  Bring  the  level  of  the  sodium  hydroxide  and  the  alkaline  pyro- 
gallate in  the  capillary  tubes  to  their  respective  wires,  or  set  the  wires 
to  the  menisci. 


AIB  SEBVIOE  MEDICAL.  873 

3.  Set  the  level  of  the  temperature-control  tube. 

4.  Take  the  sample. 

5.  After  two  minutes  read  the  volume  of  the  sample. 

C.  Absorb  the  CO2.  Bring  the  sodium  hydroxide  to  the  wire.  Head 
the  volume  after  two  minutes.  (Samples  from  the  rebreathing  ma- 
chine do  not  ordinarily  contain  CO2,  so  this  step  may  be  omitted. ) 

7.  Absorb  the  0,  and  bring  the  pyrogallate  to  the  wire.  Read  the 
volume  after  two  minutes. 

CAKE  OF  THE  APPARATUS. 

Cleaning. — Whenever  large  drops  stand  on  the  inside  of  the  glass 
burette  and  temperature-control  tubes  two  or  three  minutes  after 
the  fluid  has  fallen,  it  is  an  indication  that  the  tubes  need  cleaning. 
This  may  be  done  by  drawing  cleaning  fluid  into  the  tubes.  The 
tubes  must  first  be  drained  by  opening  the  stopcocks,  lowering  the 
leveling  bottle  and  disconnecting  it.  The  fasteners  at  the  top  and 
bottom  of  the  burette  should  be  removed  and  the  rubber  discon- 
nected at  the  top  of  the  burette.  This  will  allow  the  burette,  con- 
trol tubes,  and  jacket  to  be  moved  forward  in  the  slot  as  one  piece. 
The  lower  free  ends  of  the  two  tubes  may  then  be  put  in  a  beaker  of 
cleaning  fluid  and  the  solution  sucked  up  by  means  of  rubber  tubing 
attached  to  the  top  of  the  tubes.  This  solution  should  stand  in  the 
tubes  several  hours,  or  even  over  night.  All  traces  of  cleaning  fluid 
are  removed  by  repeatedly  filling  the  tubes  with  water. 

The  capillary  tubing  may  be  cleaned,  after  dismounting  it,  by 
washing  it  out  with  cleaning  fluid,  rinsing  it  with  water,  and  drying 
out  with  alcohol. 

Formula  for  cleaning  fuid. — The  cleaning  fluid  connnonly  used 
consists  of  a  strong  solution  of  sulphuric  acid  in  which  potassium 
bichromate  is  dissolved.  A  layer  of  solid  bichromate  should  always  be 
kept  in  the  bottom  of  the  bottle.  This  solution  can  be  used  over  and 
over  again. 

Stopcocks. — The  stopcocks  should  always  work  freely,  but  should 
never  be  loose  enough  to  leak.  A  light  layer  of  vaseline  or  preferably 
of  a  lubrication  mixture,  should  be  rubbed  on  the  stopcocks.  Too 
much  lubricant  is  liable  to  plug  the  capillary  tubes.  A  good  grease 
is  made  by  melting  vaseline  and  beeswax  in  the  proportions  of  3  to  1. 
Another  formula  is  as  follows  (Dennis,  Gas  Analysis,  p.  115)  : 

1.  Melt  together  12  parts  by  weight  of  vaseline  and  1  part  of  par- 
affin.   Do  not  heat  enough  to  give  off  fumes. 

2.  Take  parts  by  weight  of  finely  chopped  soft  black  rubber. 
Add  No.  2  to  No.  1  slowly  as  the  latter  is  dissolved,  while  heating 

over  a  low  flame.  When  most  of  the  rubber  is  added,  test  it  by  pull- 
ing it  between  the  thumb  and  forefinger.  AMien  it  is  of  the  right 
consistency  it  should  pull  into  cobwebby  threads. 


374  AIR   SERVICE   MEDICAL. 

Rubber  connections. — Rubber  connection  pieces  should  be  removed 
before  cleaning  fluid  is  used.  If  the  rubber  sticks  to  the  glass  it  may 
be  loosened  by  inserting  the  point  of  a  penknife  between  the  tube  and 
the  glass.  A  drop  of  water  put  under  the  knife  blade  sometimes 
helps.  New  rubber  connections  will  slip  on  easily  if  the  end  of  the 
glass  tubing  is  moistened  with  water. 

If  a  leak  in  the  system  is  suspected,  raise  the  leveling  bottle  until 
the  sample  tube  is  filled  Avith  about  18  cubic  centimeters,  close  all 
the  stopcocks  and  lower  the  leveling  bottle  as  far  as  possible.  Read- 
ings of  the  maniscus  from  time  to  time  will  be  the  same  if  no  leak  is 
present.  If  the  level  of  the  sodium  hydroxide  and  the  alkaline 
pyrogallate  in  the  capillary  tubes  will  not  stay  at  the  wire  Avhen  the 
stopcocks  are  closed,  either  the  rubber  connections  or  the  stopcocks 
are  leaking. 

Red  rubber  should  not  be  used  on  the  connections  where  alkali 
will  touch  it,  as  it  gives  off  sulphur,  which  may  finallj'  appear  as 
hydrogen  sulphide  in  the  burette. 

It  may  be  necessary  to  make  the  rubber  connections  tight.  This 
may  be  done  with  a  flexible  wire,  or  more  convenientl}'  with  rubber 
bands.  Loop  the  band  around  the  rubber  tube,  pull  tight,  and  wrap 
the  free  end  around  the  tube  several  times,  finally  passing  it  under 
the  wrapping  with  the  aid  of  the  curved  forceps. 

A  check  on  calibration,  tightness  on  joints,  and  the  efficiency  of 
absorbents  can  be  made  by  analyzing  atmospheric  air.  If  the  appa- 
ratus is  properly  graduated  and  in  good  order,  the  sum  of  the  oxy- 
gen and  the  carbon  dioxide  in  uncontaminated  atmospheric  air  should 
be  20.96  per  cent. 

The  scale  etched  in  the  burette  tube  may  be  made  more  visible  if 
blue  crayon  is  rubbed  on  it  and  a  piece  of  white  paper  put  behind  it 
but  not  pasted  on  the  burette. 

The  analyst  must  remember  that  the  accuracy  in  the  use  of  the 
apparatus  depends  more  on  making  sure  that  absorptions  are  com- 
plete than  upon  extreme  effort  to  read  the  burette  as  finely  as  pos- 
sible. It  is  essential,  therefore,  after  an  absorption  is  supposedly 
complete,  to  pass  the. gas  over  again  into  the  absorbent  and  make 
another  reading  to  be  sure  that  no  change  occurs. 

Solutions  used  as  absorbents. — A  10  per  cent  solution  of  sodium 
hydroxide  is  used  to  absorb  CO,.  A  10  per  cent  solution  signifies 
that  in  each  100  grams  of  solution  there  are  10  grams  of  the  substance 
dissolved.  Weigh  out  about  10  grams  of  sodium  hydroxide  and  add 
water  to  make  100  cubic  centimeters. 

The  absorbent  for  oxygen  consists  of  pyrogallic  acid  in  a  nearly 
concentrated  potassium  hydroxide  solution  in  the  proportions  of  10 
grams  of  pyrogallic  acid  in  each  100  cubic  centimeters  of  KOH  of  a 
specific  gi-avity  of  1.55.     A  hydrometer  may  be  used  to  make  up 


AIR   SERVICE    MEDICAL.  875 

the  KOH  solution,  or  767  grams  of  1,000  cubic  centimeters  of  water 
gives  a  specific  gravity  of  1.55. 

The  absorber  should  be  about  two-thirds  filled  with  the  absorbent, 
and  a  one-quarter  inch  layer  of  liquid  petrolatum  should  be  used  to 
protect  the  absorbent  from  the  air.  One  filling  with  alkaline  pyrogal- 
lic  will  last  for  more  than  100  analyses.  When  the  O2  absorption  be- 
comes sluggish,  the  pyrogallate  should  be  changed,  but  mere  stand- 
ing in  the  pipette  does  not  cause  it  to  deteriorate.  The  pyrogallate 
should  be  made  more  exactly  in  the  manner  described,  for  both  weaker 
and  stronger  solutions  do  not  absorb  so  well. 

In  renewing  the  sodium  hydroxide  or  the  alkaline  pyrogallate, 
care  should  be  taken  not  to  get  the  oil  on  the  absorbing  surfaces. 
This  may  be  avoided  by  first  removing  the  oil  w^ith  a  pipette.  Or  it 
may  be  necessary  to  siphon  off  the  greater  part  of  the  old  solution 
through  the  capillary  tube.  In  this  case  the  lower  surface  of  the 
oil  should  not  be  allowed  to  come  to  the  lower  edge  of  the  absorbing 
tube.  New  solution  may  then  be  added  through  the  capillary  tube 
and  the  oil  will  remain  on  top  and  inside  of  the  absorbing  tube  as 
before. 

It  has  been  found  convenient  to  use  in  the  leveling  bottle  a  1  per 
cent  to  2  per  cent  sulphuric-acid  solution  in  50  per  cent  ethyl  alcohol. 
The  alcohol  reduces  the  surface  tension  and  permits  more  rapid  and 
thorough  drainage.    It  also  acts  as  a  self-cleaner  for  the  burettes. 


I 


CHAPTER  VIII. 
THE  WORK  OF  THE  FLIGHT  SURGEON. 


When  the  Flight  Surgeons  were  sent  to  the  various  flying  schools, 
it  was  realized  that  local  conditions  in  the  different  schools  varied 
widely,  and  the  following  general  instructions  were  therefore  issued 
June  27  for  general  information  regarding  duties  of  a  FLIGHT 
SURGEON. 

The  "Flight  Surgeon"  is  new.  It  would  be  unwise  to  decide  at  once 
as  to  every  intimate  detail  of  his  duties. 

Each  Flight  Surgeon  is  to  study  all  local  details  of  his  post  and 
send  in  a  report  to  this  office,  as  to  local  conditions,  one  week  after 
his  arrival. 

If  he  has  not  received  the  entire  equipment  for  complete  reexami- 
nation of  the  fliers,  he  will  notify  this  office  what  is  lacking. 

It  is  planned  that  he  shall  reexamine,  routinely,  every  individual 
flier  in  the  command  once  every  two  months.  The  reexamination 
will  be  limited  to  the  cardio-vascular,  turning-chair,  and  eye  tests. 
In  the  routine  examination  of  the  eye,  it  will  not  be  necessary  to  make 
ophthalmoscopic  examination. 

The  Flight  Surgeon  is  directed  to  notify  this  office  how  many  fliers 
he  will  be  able  to  examine  daily,  under  the  conditions  at  his  post. 
He  will  also  notify  this  office  regarding  the  medical  personnel 
under  the  post  surgeon  at  his  school,  and  state  along  exactly  what 
special  lines  these  medical  officers  are  able  to  help  him  in  his  work, 
in  addition  to  their  other  duties. 

There  is  a  sharp  distinction  between  the  original  examination  and 
this  reexamination.  In  the  original  examination  the  duty  of  the 
examiner  was  to  eliminate  the  unfit.  This  was  the  primary  object, 
in  order  that  the  highest  type  of  men  should  be  selected  for  our 
aviation  service.  In  sharp  contrast,  the  primary  object  of  the  re- 
examination is  that  the  aviator  may  be  KEPT  IN  THE  SERVICE 
for  the  longest  possible  usefulness  as  a  flier.  The  Flight  Surgeon  is 
not  placed  in  a  flying  school  for  the  primary  purpose  of  "  weeding 
out "  those  who  should  not  have  been  allowed  to  enter  the  service,  be- 
cause of  a  poorly  conducted  original  examination.    It  goes  without 

377 


378  AIK   SERVICE   MEDICAL. 

saying  that  any  man  who,  by  the  reexamination,  proves  to  be  unfit, 
and  M^io  obviously  never  will  be  fit  to  be  an  aviator,  should  be  recom- 
mended for  discharge.  But  this  is  by  no  means  the  essential  and  pri- 
mary reason  for  having  a  Flight  Surgeon  in  each  flying  school.  In 
order  that  no  mistakes  may  be  made  in  this  matter,  it  will  be  neces- 
sary for  the  Flight  Surgeon  to  consult  this  office,  supplying  all  neces- 
sary information,  before  he  will  be  allowed  to  recommend  the  dis- 
charge of  an}^  cadet  who  has  already  been  under  instruction.  The 
fundamental  principle  of  the  service  of  the  Flight  Surgeon  must  be 
emphasized  and  understood  by  everyone  in  the  command  from  the 
Commanding  Officer  down — namely,  the  Flight  Surgeon's  function  is 
to  keep  the  members  of  the  command  mentally  and  physically  fit,  and 
by  so  doing  to  prolong  their  usefulness  in  the  service.  If  the  Flight 
Surgeon  were  to  act  as  a  "  watchdog  "  sent  to  remove  men  from  the 
service  after  they  have  had  experience  in  flying  and  are  perhaps  just 
about  to  receive  their  commissions,  his  usefulness  would  be  reduced 
95  per  cent,  and  the  necessary  confidence  and  cooperation  on  the 
part  of  the  Commanding  Officer  and  the  fliers  would  justly  be  with- 
held. 

At  certain  of  the  fields  the  work  of  the  Flight  Surgeon  will  be 
supplemented  by  a  Branch  Medical  Laboratory ;  at  many  of  the  fields 
there  will  be  no  such  branch  laboratory. 

The  work  of  the  Flight  Surgeon  and  of  the  Laboratory  Unit  should 
be  intimately  coordinated.  There  must  be  established  a  spirit  of 
willing  cooperation;  with  single-minded  assistance  on  the  part  of 
both.  There  will  be  assured  successful  results  and  efficient  progress. 
The  Branch  Medical  Laboratory  will  have  two  uses — one,  the  ex- 
amination work  for  classification  of  the  flier;  two,  examinations  for 
assisting  the  Flight  Surgeon  in  his  work  in  the  care  of  the  flier. 
The  result  of  these  latter  examinations  are  reported  to  the  Flight 
Surgeon,  who  alone  makes  the  decision  as  to  the  fitness  of  the  in- 
dividual to  fly. 

In  preparing  the  reexamination  blank,  it  was  recognized  that  all 
tests  should  be  carefully  considered.  The  ideal  form  of  reexamina- 
tion would  include  only  tests  of  the  essential  things;  nothing  essen- 
tial must  be  omitted.  At  the  same  time  it  was  recognized  that  if  all 
the  fliers  of  the  Air  Service  are  to  be  examined  according  to  this 
blank  every  two  months  (and  such  reexaminations  soon  run  into 
hundreds  of  thousands)  e^erj^  unessential  item  such  as  height  or  a 
study  of  the  joints  should,  of  course,  be  left  out.  In  this  way  there 
would  be  a  great  deal  of  time  saved  for  the  Flight  Surgeon,  With 
this  object  in  mind,  the  following  reexamination  blank  was  put  into 
iise: 


AIK    SERVICE    MEDICAL.  379 

REEXAMINATIOX    OF   AVIATOR. 

Divmon  of  military  aeronautics. 

All  officers  drawing  flying  pay  will  bo  roiiuired  to  take  the  follow- 
ing examination  semiann\ially,  and  it  will  be  filed  as  a  permanent 
record  of  the  flying  status  of  this  officer. 

Name Placej 

Status 

Age Date 

GENERAL. 

(Stripped  to  the  Avaist.) 

1.  Pulse: 

After  5  minutes  reclining 

On  standing 

After  standard  exercise  ^ 

Two  minutes  after  exercise 

2.  Breath  held,  seconds 

3.  Heart  function 

4.  Blood  pressure :  Systolic  (  )  Diastolic  (  ) 

5.  Haemoglobin    percentage 

EAR. 

<i.  Test  of  internal  ears.  VIII  nerves,  brain-stem  and  cerebellum. 

{a)   Is  nystagmus  present  on  loking  straight  ahead? 

ih)  Turning-chair.    Head  tilted  30  degi-ees  forward.    Eyes  closed. 

{x)   Nystagmus,  after  turning  to  right left 

iy)  Pointing: 

(1)  Before  turning:  Right  arm left  arm 

(2)  After  turning  to  right:  Eight  arm left 

arm 

(3)  After   turning   to    left:    Right    arm left 

arm 

{z)  Falling: 

(1)  After  turning  to  right 

(2)  After  turning  to  left 

EYE. 

7.  Ocular  movements 

8.  Visual   acuity:   Right left 

9.  Muscle   balance:    Esophoria Exophoria Hyperphoria 

10.  Near-point  for  accommodation  (each  eye  separatelv)  R.  E 

L.  E 

1  standard  exercise  will  consist  of  placing  right  foot  on  a  chair  and  then  stepping  up 
on  the  chair  from  the  floor  five  times. 


380  AIE  SEB7I0E  MEDICAL. 

11.  Near-point  for  convergence 

12.  Prism  divergence  (if  any  heterphoria  present) 

13.  Pupillary  reactions:  Direct:     Consensual:     Accommodation: 

(a)  Right  eye 

(h)  Left  eye 

Remarks: 

Name , 

Rank , 

Flight  Surgeon. 
The  Flight  Surgeon  makes  his  weekly  report  on  a  special  blank. 
The  statistics  from  these  reports  are  then  made  up  on  the  monthly 
blank. 

War  Department  Air  Service  Division,  S.  G.  O. 

Care  of  Flier  Report. 

Station 

'  Week  ending 

Commanding  Officer. 

1.  Number  of  fliers  flying  at  flying  school 

2.  Total  hours  of  flying  for  week 

3.  Total  number  of  flights  for  week 

4.  Number  of  fliers  voluntarily  reporting  sick  to  the  Flight  Surgeon 

5.  Number  of  fliers  found  physically  unfit  either  by  the  Flight  Surgeon  or  the 

Physical  Director 

6.  Number  of  fliers  retained  for  flying  who  would  otherwise  have  been  disqualified 

by  Flight  Commander 

7.  Number  of  fliers  who  have  been  permanently  disqualified  by  the  Commanding 

Officer  through  suggestions  from  the  Flight  Surgeon 

8.  Number  of  hours  of  j^hysical  training  given  to  fliers  by  Physical  Director— this 

to  apply  to  physical  training  given  in  classes  only 

9.  Number  of  reqiiests  made  by  Flight  Surgeon  to  Commanding  Officer  for  candidates 

to  rest,  due  to  impaired  physical  condition 

10.  Number  of  fatal  injuries  from  crashes 

11.  Crashes  (special  report  attached) 

12.  Special  cases.     (Any  unusual  cases  during  the  Aveek,  or  any  data  which  may 

be  of  unusual  value  to  this  office,  note  fully  on  back  of  this  report) 


Flight  Surgeon. 


War  Department,  Air  Service  Division,  S.  G.  O. 
Special  Report  by  Flight  S^irgeons. 

CRASHES. 

Fatal  injury 

Injured 

Not  injured 

Station 

Date  of  Crash 


Commanding  Officer. 


AIE  SEBVTCE  MEDICAL,  381 


Name Age 

Type  of  machine 

Weather Accldeut  occurred  I 

Time  of  day 

Day  of  week 

Approximate  altitude  at  which  trouble  began 

f  Engine 

Was  accldeut  due  to  defect  in  the  airplane  greakaee 

Date  of  last  examination  of  aviator 

Total  hours  dual  instruction  before  doing  first  solo 

Total  hours  solo Length  of  flight  before  crashing 

How  many  flights  made  previous  to  crash 

Extent  of  damage  to  airplane 

Amount  and  nature  of  work  perfoimed  before  flight 

State  what  was  the  cause  of  crash,  in  your  judgment 


Getting  off. 
In  the  air_. 
Landing 


Remarks  in  full ; 


Plight  Surgeon. 

This  being  essentially  a  new  type  of  service,  returns  are  as  yet 
irregular.  Although  statistics  are  available  for  two  months  only, 
from  a  limited  number  of  fields,  they  already  reveal  some  points  of 
particular  value. 

During  the  month  of  July  returns  have  come  in  from  14  fields. 
The  average  total  of  fliers  at  these  fields  was  3,113.  The  average 
number  of  hours  of  flying  for  each  person  13.4,  the  average  number 
of  flights  for  each  person  per  month,  13.5. 

The  number  of  fliers  who  voluntarily  reported  for  advice  to  the 
Flight  Surgeon  during  the  month  was  1,185,  or  38.1  per  cent  of  the 
total  number  at  the  14  fields.  This  refers  to  every  sick  visit,  and 
without  doubt  many  fliers  have  reported  more  than  once. 

The  number  of  fliers  found  temporarily  unfit  by  the  Flight  Surgeon 
or  Physical  Director  and  temporarily  taken  off  flying  was  269,  or  8.6 
per  cent. 

The  number  of  fliers  retained  for  flying  by  the  Flight  Surgeon  who 
would  otherwise  have  been  disqualified  by  the  Flight  Commander  was 
20,  or  0.6  per  cent.  The  number  of  fliers  permanently  disqualified 
by  the  Commanding  Officer  through  suggestions  of  the  Flight  Sur- 
geon, 14,  or  0.4  per  cent. 

The  number  of  requests  made  by  Flight  Surgeons  to  Commanding 
Officers  for  candidates  to  rest,  due  to  impaired  physical  condition, 
137,  or  4.4  per  cent. 

The  number  of  crashes  was  87,  or  2.8  per  cent,  and  the  number  of 
fatal  injuries  resulting  from  crashes,  14,  or  0.4  per  cent. 


382 


AIR    SERVICE    MEDICAL. 


The  number  of  those  who  voluntarily  reported  for  advice  to  the 
Flight  Surgeon,  arranged  according  to  field,  is  as  follows : 


Field  (July). 

Average 

number  of 

cadets  at 

flv-ing 

school. 

Number  of 
fliers  volun- 
tarily re- 
porting for 
advice  to 

Flight 
Surgeon. 

Barron  Field 

177 
157 
122 
100 
160 
592 
177 
135 
197 
405 
114 
153 
114 
510 

136 

Brooks  Field 



60 

Call  Field 

82 

Carlstrom  Field 

18 

Carruthers  Field '. 

Kelly  Field 

334 

Love  Field 

160 

Mather  Field 

4 

Park  Field 

125 

Post  Field 

.                              _ 

180 

Rich  Field 

24 

Rockwell  Field 

35 

Taliafeno  Field 

4 

Taylor  Field 

23 

Total 

3,113 

1,185 

Fourteen  fields  IvAve  sent  in  reports  for  August.  The  average  total 
number  of  fliers  at  these  fields  was  2,963.  The  total  number  of  hours 
flying  for  each  person  was  21,  and  the  average  number  of  flights  26.6. 

The  number  of  fliers  who  voluntarily  reported  for  advice  to  the 
Flight  Surgeon  during  this  month  was  1,329,  or  44.9  per  cent  of  the 
number  of  fliers.    This  shows  an  increase  of  6.8  per  cent  over  July. 

The  number  of  fliers  found  temporarily  unfit  by  the  Flight  Sur- 
geon, or  Physical  Director,  was  366.  or  12.4  per  cent. 

The  number  of  fliers  retained  for  flvinff  bv  the  Flight  Surijeon  who 
Avould  have  otherwise  been  disqualified  by  the  Flight  Commander  was 
12,  or  0.4  per  cent. 

The  number  of  fliers  permanently  disqualified  by  the  Command- 
ing Officer  through  suggestion  of  the  Flight  Surgeon,  18,  or  0.6 
per  cent. 

The  number  of  requests  made  by  Flight  Surgeons  to  Commanding 
Officers  for  fliers  to  rest,  due  to  impaired  physical  condition,  248,  or 
8.4  per  cent. 

The  number  of  crashes  was  141,  or  4.8  per  cent,  and  the  number  of 
fatal  injuries  18.  or  0,6  per  cent. 

The  number  of  those  who  voluntarily  reported  for  advice  to  the 
Flight  Surgeon,  arranged  according  to  fields,  is  as  follows : 


383b-l 


CO 

»— I 

o 

a 


383b-2 


.\1H    SERVICE   MEDICAL 


"-  383 


Field  (August). 

Average 

number  of 

cadets  at 

flying 

.school. 

Number  of 
fliers  volun- 
tarily re- 
porting for 
advice  to 

Flight 
Surgeon. 

Barron  Field 

166 
149 
72 
42 
160 
234 
588 
569 
173 
140 
117 
155 
263 
135 

159 

Brooks  Field 

93 

CallField 

37 

Carlstrom  Field 

• 

28 

Carruthers  Field 

21 

Chanute  Field 

61 

Ellington  Field 

144 

Kellv  Field 

584 

.Mather  Field 

29 

Park  Field 

32 

Rich  Field 

55 

Rockwell  Field 

21 

Taliaferro  Field 

28 

Taylor  Field ... 

47 

Total 

2,963 

1,329 

The  Flight  Surgeon  makes  it  his  particular  business  to  gather  from 
every  ix)ssible  source  every  bit  of  information.  His  reports  are  to 
be  based  upon  the  opinions  of  everyone  who  knows  anything  of 
the  crashes,  from  the  Commanding  Officer  down. 

From  the  limited  number  of  flying  fields  to  which  Flight  Surgeons 
are  already  assigned  have  come  reports  of  210  crashes.  49,  or 
23.3  per  cent,  of  these  were  due  to  engine  defects;  4  to  some  de- 
fect in  the  body  of  the  machine;  and  7,  where  the  cause  of  crash 
could  not  be  definitely  attributed  to  a  defect  in  the  aeroplane.  The 
crash  was  reported  with  reference  to  the  pilot  only,  no  record  being 
made  of  other  passengers. 

In  these  210  crashes  the  pilot  Avas  fatally  injured  in  23  cases 
(10.9  per  cent)  ;  injured  slightly  or  seriously  in  64  cases  (30.5  per 
cent) ;  in  123  cases  (58.6  per  cent)  he  escaped  uninjured. 

One  hundred  and  forty-eight  falls,  or  70.5  per  cent,  were  due  to 
'•  poor  judgment."  Although  some  physical  or  mental  unfitness  may 
have  contributed  to  this  cause,  there  is  nothing  in  the  report  or  in 
the  re-examination  which  would  indicate  it.  Xo  doubt  some  of  them 
occurred  through  a  temporary  condition  brought  on  by  fatigue,  ex- 
treme heat,  etc. 

It  is  to  be  noted  that,  compared  to  the  90  per  cent — referred  to 
in  Part  I,  chapter  4,  of  this  book — this  report  shows  a  comparatively 
small  number  of  deaths  and  injuries  directly  traceable  to  the  physi- 
cal or  mental  unfitness  of  the  pilot. 

There  Avere  two  crashes  in  which  "  poor  judgment  through  physical 
impairment "  Avas  the  cause.  In  one  the  pilot  failed  to  level  off 
soon  enough.  He  Avas  rated  as  "  rather  poor  material,  sluggish 
vestibular  apparatus;  Aveak  on  stereoscope,  muscle  balance,  Exo.  2." 
The  second  case  Avas  one  of  fatigue,  pure  and  simple. 


384  AIE  SEBVIOE  MEDICAL, 

Two  crashes  were  due  to  "  acute  physical  impairment."  The  first 
an  acute  frontal  sinuitis.  During  his  examination  he  told  the  Flight 
Surgeon  of  the  accident.  Said  he  could  not  act  quickly  enough. 
Head  felt  dull,  heavy,  and  not  right.  It  was  recommended  that 
he  be  taken  off  flying  until  the  condition  cleared  up.  The  recom- 
mendation was  approved,  and  he  was  put  under  the  care  of  the 
Flight  Surgeon. 

The  other  crash  was  caused  by  the  pilot  probably  fainting,  due  to 
extreme  heat. 

Of  these  210  crashes,  there  were: 

Collisions  (in  air) 21 

Side  slips , 11 

Stalls  18 

Tail  spins , , 44 

Nose   dives 8 

Stall  and  spin l' 

Bad  landings 81 

Taxiing  (collision  on  ground) 11 

Unknown    , 14 

Reverse    glide 1 

Total 210 

Of  these  crashes  38.6  per  cent  were  due  to  bad  landings,  21  per  cent 
to  tail  spins,  and  other  spins,  and  10  per  cent  to  "  collisions  "  in  air. 
There  was  one  crash  due  to  a  reverse  glide.  There  are  very  few  cases 
known.  "  Ship  seemed  to  go  into  reverse  glide  apparently  while 
attempting  to  loop  at  an  altitude  of  2,000  feet.  Descended  in  same 
position,  with  one  or  two  attempts  to  turn,  and  crashed  down. 
Controls  were  intact,  and  no  definite  reason  can  be  given  for  cause 
of  accident.     Pilot  and  instructor  killed  immediately." 

It  must  be  emphasized  that  21  per  cent  of  all  the  crashes  were 
directly  traceable  to  failure  to  come  out  of  spinning  nose  dives  and 
other  turning  evolutions.  This  21  per  cent  can  be  largely  eliminated 
by  the  Ruggles  Orientator.  Crashes  due  to  failure  to  come  out  of 
such  stunting  evolutions  occur  entirely  among  cadets  who  are  un- 
familiar with  the  sensations  produced  by  these  unusual  movements. 
The  Ruggles  Orientator  will  make  them  perfectly  familiar  with  all 
these  turning  sensations  before  they  go  up. 

The  Flight  Surgeon  is  definitely  Instructed  to  consider  himself  au- 
thorized at  all  times  to  make  independent  investigations  of  condi- 
tions in  any  way  bearing  upon  the  health  and  fitness  of  the  fliers 
and  forward  such  reports  direct  to  the  office  in  order  that  each  Flight 
Surgeon's  experience  in  this  way  might  be  rendered  available  to  the 
Flight  Surgeons  in  other  fields. 

All  of  the  above  constitutes  the  official  routine  of  the  Flight  Sur- 
geon's work.    During  the  early  months  of  the  Flight  Surgeon's  activi- 


en 

<^ 

H 
►— I 

CO 

O 
W 


3841) 


AIE  SEBVIOE   MEDICAL.  886 

ties,  naturally,  a  large  bulk  of  his  reports  were  made  up  of  his  own 
personal  observations  and  methods  of  making  himself  valuable  to 
the  Commanding  Officer  and  to  the  fliers.  The  wisdom  of  allowing 
a  wide  latitude  to  the  Flight  Surgeon  in  developing  his  work  has  been 
proven  by  the  original  work  that  has  been  done  by  the  various  Flight 
Surgeons  on  their  own  initiative.  Naturally,  when  the  Flight  Sur- 
geon arrived  at  the  fields,  each  cadet  felt  that  he  had  come  to  remove 
from  the  service  those  who  were  not  "  absolutely  perfect." 

This  idea  was  soon  disposed  of.  The  Flight  Surgeon  gained  the 
confidence  of  the  men  through  informal  talks  given  in  the  barracks 
or  at  the  Flight  Surgeon's  quarters  or  through  personal  interviews 
at  his  office,  where  the  men  were  encouraged  to  come  and  discuss 
their  personal  difficulties.  To  quote  one  Flight  Surgeon:  "If  I  ever 
have  as  many  patients  in  private  life  as  I  have  here,  I  will  make  at 
least  $100,000  a  year  and  buy  Liberty  bonds.  In  came  the  lame  and 
halt  and  then  some.  I  have  had  to  handle  about  every  thing  from  a 
man  with  a  sick  mother  to  a  man  with  imaginary  lumps  on  his  chest ; 
from  diplopia  to  love  affairs."  This  same  Flight  Surgeon  picked  two 
typical  cases  of  ''  staleness "  for  whom  he  secured  leave  of  absence. 
He  discovered  many  others  who  needed  a  change  of  environment  for 
a  few  days  and  made  this  possible  by  enlisting  the  interest  of  a 
kindly  hostess  in  the  adjacent  citj'^;  these  cadets  were  allowed  to  visit 
at  this  home  for  week-ends.  Others  are  maldng  wise  suggestions 
as  to  flying  hours  during  the  excessive  heat  of  southern  camps; 
another  has  arranged  a  longer  period  of  sleep  for  his  men :  one  has 
substituted  fruit  juices  for  harmful  drinks  at  the  post  exchange. 
The  men  are  being  carefully  reexamined  from  time  to  time,  so  that 
any  abnormal  condition  may  be  alleviated  by  proper  measures.  In 
lectures  the  necessity  of  a  clean  mind  in  a  clean  body  is  being  im- 
pressed upon  them ;  that  success  does  not  follow  in  the  wake  of  excess. 

The  following  are  typical  excerpts  from  Flight  Surgeon  reports: 

Two  tliei's  had  nijpeared  before  their  Comiiianding  Oflicer  just  pinor  to  my 
ai-rival.  They  had  been  summoned  because  it  had  become  apparent  through 
the  observations  of  the  Flight  Commander  that  they  had  reached  a  condition 
which  did  not  justify  continuing  them  In  flying  service.  Their  Commanding 
Officer  decided  to  order  them  away  for  four  months.  I  was  able  to  demonstrate 
that  the  first  of  these  fliers  was  suffei'ing  from  diplopia  ("an  eye  condition 
which  is  incompatible  with  flying");  the  second  was  found  to  be  perfectly 
normal  except  for  obstinate  constipation.  A  dose  of  castor  oil  and  in- 
jections put  this  man  into  perfect  condition,  and  he  resumed  flying  duty  in  a 
few  days. 

The  Flight  Surgeon  was  in  the  first  instance  the  means  of  avoiding 
continuing  as  attached  to  the  flying  service  a  definitely  unsafe  indi- 
vidual, and,  in  the  second  instance,  was  able  to  restore  to  the  service, 
within  a  few  days,  a  perfectly  good  flier,  who  otherwise  would  have 
been  out  of  the  service  for  four  months. 


386  AIK    SERVICE    MEDICAL. 

Another  case  was  that  of  a  flier  who  had  within  a  relatively  short  time 
crashed  six  planes.  Examination  revealed  an  eye  condition  directly  resix>n- 
s'ble  for  this  series  of  crashes. 

In  several  of  the  flying  schools  there  occurred  epidemics  of 
mumps;  one  of  the  complications  peculiar  to  mumps  is  the  impair- 
ment of  that  part  of  the  internal  ear  which  is  directly  concerned  in 
flying.  One  of  the  first  reports  to  come  in  showed  a  number  of 
instances  of  impairment  of  flying  ability  traceable  directly  to  this 
complication.  These  individuals  to  all  appearances  had  made  per- 
fect recoveries. 

A  flier  Avith  a  long  record  of  excellent  flying  ability  was  noted  by 
his  Flight  Commander  to  be  fljnng  progressively  worse  and  worse. 
After  several  crashes  he  was  ordered  out  of  active  flying  service.  He 
then  was  sent  to  another  post  where  he  was  examined  by  a  Flight  Sur- 
geon, who  found  that  lie  had  a  progressively  increasing  impairment 
of  his  internal  ears :  this  had  reached  the  degree  of  practical  destruc- 
tion of  both  internal  ears.  The  Flight  Surgeon  compared  these  findings 
with  his  record  and  recognized  that  some  infection  mu.st  have  occurred 
to  destroy  this  special  sense.  He  then,  on  careful  questioning,  suc- 
ceeded in  eliciting  the  history  of  specific  infection,  which  had  oc- 
curred after  his  entrance  into  service  and  only  two  months  prior  to 
this  last  examination. 

The  following  cases  illustrate  the  value  of  Flight  Surgeon  service 
in  analyzing  conditions  of  temperament  and  mental  poise.  One 
flier,  on  examination,  showed  slight  motor  restlessness,  decided  volu- 
bility, general  aggressive  mental  attitude,  associated  with  an  assump- 
tion of  an  unusual  degree  of  confidence  in  his  ability.  This  group  of 
symptoms  indicated  at  once  to  the  Flight  Surgeon  the  probable  danger 
of  permitting  him  to  fly,  and  the  Commanding  Officer  was  notified  to 
that  effect.  Although  forbidden  to  go  into  the  air.  within  48  hours 
after  this  examination  the  aviator  made  a  cross-country  flight  and 
eixled  with  a  bad  crash.  Following  this,  the  symptoms  already  noted 
were  greatly  exaggerated,  and  he  passed  into  a  well-defined  attack  of 
manic-depressive  insanity. 

The  result  of  the  examination  of  the  following  case  is  of  particular 
value :  The  Flight  Commander  reconnnended  that  a  certain  flier  dis- 
continue flying  until  a  complete  physical  examination  could  be  made 
with  a  Aiew  of  determining  his  fitness  for  flying.  At  the  time,  this 
flier  was  giving  instructions  in  acrobatics,  and  his  own  vicious  habits 
and  stunting  at  low  altitudes  brought  about  this  recommendation. 
The  Flight  Surgeon  discovered  a  very  abnormal  blood  pressure  and 
pulse  pressure,  and  an  examination  of  the  urine  disclosed  disease 
of  the  kidneys. 

A  different  type  of  case  is  the  following:  Cadet  reported  to  the 
Flight  Surgeon  that  he  had  been  losing  sleep  because  of  a  problem  of 


AIR  SERVICE   MEDICAL.  387 

an  intimate  personal  nature.  Examination  elicited  the  fact  that  his 
family  relations  were  perfectly  satisfactory.  His  family  history 
was  excellent;  no  hereditary  burden  ;  previous  home  life  conducive  to 
healthy  growth.  He  had  completed  high  school  and  two  years  of 
his  college  course ;  had  had  seven  hours  of  solo  flying,  with  excellent 
record.  His  general  habits  were  good,  and  his  trouble  was  purely 
imaginary,  in  the  matter  of  the  supposed  attitude  of  his  fellow  cadets 
toward  him.  He  Avas  nursing  an  imaginaVy  grievance  and  this  was 
the  only  maladjustment  in  his  mental  poise.  He  wanted  some 
pow'ders  to  put  him  to  sleep.  A  3-mile  walk,  and  a  cold  shower  were 
prescribed  instead,  and  he  was  given  a  slap  on  the  back  with  a 
hearty  "  You're  all  right."  Several  days  later  he  reported  that  he  had 
had  the  first  good  night's  sleep  in  five  weeks,  and  he  was  restored  to 
flying  status  without  further  attention. 

The  following  constitutes  extracts  from  reports  from  Flight  Sui-- 


geons : 


CKASH    ON    LANDING. 


Instructor's  report:  Bad  landing  caused  the  machine  to  porpoise  and  he  did 
not  use  his  motor  or  level  the  machine,  hut  simply  allowed  it  to  nose  right 
into  the  ground. 

Cadet's  report:  Landed  too  fast,  and  as  we  bounced  up  and  down  on  the 
ground,  the  throttle  popped  partly  open. 

Flight  Surgeon's  report:  Cadet reported  to  me  after  this  accident,  and 

I  asked  him  why  he  did  not  level  off  properly  or  give  the  ship  gas  when  he 
bounced.  He  stated  that  at  the  time  he  knew  what  he  ought  to  do,  but  he 
simply  could  not  bring  himself  to  act  quickly  enough ;  his  head  felt  heavy  and 
he  "  did  not  feel  right." 

Examination  showed  acute  sinuitis  of  the  right  side.  This  was  sufficient  to 
affect  his  flying  judgment  and  quickness  of  decision. 

Another  Flight  Surgeon  found  that  some  accidents  were  occurring 
particularly  during  night  flying,  because  those  men  did  not  get 
sufficient  time  for  sleep  and  he  therefore  recommended  to  the  Com- 
manding Officer  a  readjustment  of  sleeping  hours.  He  has  been  eat- 
ing with  the  men  and  is  convinced  that  that  is  a  w'isc  thing  to  do,  as 
it  makes  an  excellent  opportunity  to  learn  many  things  about  the 
fliers  that  can  not  be  learned  in  any  other  w^ay. 

He  found  an  instructor  apparently  unfit  for  flying  duty.  Medical 
examination  suggested  some  toxic-absorption.  Further  examination 
revealed  badly  diseased  tonsils.  He  reported  the  case  of  one  man 
who  had  fear  that  he  would  never  be  able  to  solo  without  a  crash. 
After  a  reassuring  talk,  he  was  sent  up  for  solo  flight  the  next  day. 
He  made  good  flights  and  landings,  and  was  at  the  time  of  the 
report  a  happy  and  satisfied  pilot.  He  has  no  thought  of  leaving 
the  service,  and  could  not  be  driven  out  of  it.  This  cadet  was  dis- 
tinctly saved  for  the  service:  and  it  had  been  decided  previously  by 
the  Commanding  Officer  and  the  officers  in  charge  that  he  was  unfit 
89118—19 2ti 


388  Am  SERVICE  medical. 

and  should  be  discharged.  No  better  illustration  could  be  made  of 
the  one  predominating  function  of  the  Flight  Surgeon — keep  a  man 
in  the  service. 

As  far  as  possible,  cadets  should  be  relieved  from  sitting  around  at 
the  different  stages,  as  it  is  monotonous  and  they  become  tired  out 
from  the  inactivity.  Sleep  is  most  essential.  It  should  be  arranged 
that  the  fliers  have  at  least  eight  hours  sleep. 

Swimming  should  be  the  form  of  exercise  provided.  Calisthenics 
should  only  be  done  early  in  the  cool  of  the  morning,  and  made  short 
and  snappy ;  otherwise  they  are  exhausting  instead  of  stimulating. 

The  sale  of  soft  drinks  should  be  stopped  on  the  field  during  flying 
hours.  Many  fliers  have  gastro-intestinal  trouble,  for  which  this  is 
directly  responsible. 

The  cowl  of  the  ships  should  have  an  8-inch  arc  cut  away  in  front 
with  a  4-inch  belt  stretched  across  so  as  to  avoid  concussion  of  the 
brain  and  fracture  of  the  slaiU;  head  injuries  constitute  the  great 
majority  of  all  injuries  from  crashes. 

Inadequate  and  poorly  maintained  drinking  water  supply  for  the 
cadets  in  barracks  and  on  the  field;  remedied  by  supplying  large 
water  coolers. 

Intense  heat  prevented  the  proper  number  of  hours  of  sleep ;  rem- 
edied by  installing  ceiling  fans  in  cadet  barracks. 

Intense  heat,  110  degrees  in  the  shade,  on  the  gunnery  range;  rem- 
edied by  supplying  canvas  shelter  over  each  gun. 

Consumption  of  too  much  bottled  soda  water  and  other  soft  drinks ; 
remedied  by  supplying  lemonade. 

Quantity  and  quality  of  food  is  now  most  satisfactory;  many 
cadets  return  at  noon  from  their  Sunday  leave  in  order  to  get  their 
dinner  at  their  own  mess. 

No  matter  in  what  part  of  the  world  the  flying  field  may  be  located, 
the  observation  of  the  medical  officers  leads  to  practically  the  same 
conclusions.    This  report  is  from  an  American  flying  school  in  Italy : 

There  is  a  phase  of  aviation  which  in  every  point  of  view  is  most  important, 
and  which  is  not  receiving  the  attention  which  it  requires — regular  routine  ex- 
amination of  aviators — those  who  are  doing  advanced  flying  and  those  at  the 
front.  Much  time  and  expense  can  be  saved  if  regular  examinations  are  insti- 
tuted after  the  cadet  has  begun  flying.  The  medical  officers  of  all  aviation 
schools  should,  in  my  opinion,  have  a  course  of  instruction  in  these  special 
medical  problems  peculiar  to  aviation.  With  such  instruction  to  build  upon 
and  with  proper  application  and  observation,  each  surgeon  connected  with  the 
Air  Service  could  quickly  develop  the  ability  that  will  mean  much  to  the  Air 
Service,  in  the  settling  of  the  many  intricate  difficulties  which  necessarily  face 
the  aviator.  It  would  seem  to  me  that  the  only  way  in  which  to  carry  out  this 
work  is  to  have  a  medical  officer,  who  keeps  his  eye  on  the  flying  field  and 
watches  after  the  aviators  and  examines  them  fi'om  time  to  time  as  to  their 
mental  and  physical  fitness. 


ATB  SEEVICE  MEDICAL.  389 

I  get  up  at  4  a.  m.  with  the  cadets  and  put  in  the  day  with  them.  I  hold 
sick  call  at  5.30  and  try  to  find  out  every  cadet  that  is  not  feeling  fit  for  his 
day's  flying.  If  I  recommend  that  a  man  be  taken  off  of  flying  temporarily,  I 
have  him  report  to  me  every  morning,  and  then  I  am  able  to  tell  when  he  Is 
fit  to  return  to  the  flying  field.  I  have  already  recommended  a  man  for  dis- 
charge with  a  distinct  psychoneurosis.  I  have  completed  my  solo  flying  suSi- 
clently  to  be  ready  for  my  R.  M.  A.  test.  This  is  fine  business  and  is  going  to 
be  a  great  help  to  me  in  understanding  the  conditions  of  the  flying  game. 


CHAPTER    IX. 
THE  PHYSICAL  DIRECTOR. 


The  motors  used  in  our  airplanes  are  kept  in  perfect  running  order 
by  engineers  and  expert  mechanics,  and  the  wings  and  fusehiges 
carefully  watched  and  trued  up  and  wires  kept  taut  by  men  ayIio  are 
skilled  in  this  work.  Every  precaution  is  taken  to  have  the  machine 
fit  at  all  times,  careful  inspections  being  given  daily,  and  by  the  same 
token,  it  is  no  less  necessary  to  keep  the  human  machine  fit  for  guid- 
ing these  ships  of  the  air.  The  great  bulk  of  j^oung  men  engaged  in 
tljdng  or  learning  to  fly  in  the  United  States  Armj?^  Air  Service  come 
from  many  walks  of  life.  Naturally  some  are  better  fitted,  both  tem- 
permentally  and  physically,  to  be  made  into  aerial  warriors,  and  the 
matter  of  keeping  these  men  in  the  pink  of  condition  while  in  train- 
ing and  at  the  front  as  well,  has  presented  some  new  and  highly 
important  problems. 

To  keep  these  men  fit.  physical  directors  have  been  provided  for 
the  various  training  fields  in  our  Air  Service,  and  they  are  cooperat- 
ing with  the  flight  surgeons  not  only  in  keeping  our  men  in  the  best 
condition  possible,  but  also  in  teaching  them  how  to  increase  their 
natural  strength  and  endurance.  Thev  are  likewise  training  these 
men  to  sharpen  their  powers  of  alertness  and  quick,  cool  action,  mus- 
cular and  mental  coordination,  and  they  are  teaching  this  by  pre- 
scribing proper  living  and  carefully  supervised,  systematic  atli- 
letic  exercises. 

In  the  last  analysis,  flying  consists  of  "  knowledge  of  the  game, 
discipline,  and  physical  condition,"  and  the  physical  directors  super- 
vise the  training  in  such  a  way  that  it  has  proven  a  very  valuable 
adjunct  to  the  other  components  of  flying. 

Because  the  problem  of  handling  the  aviator  is  a  comparatively 
new  one,  and  in  view  of  the  fact  that  the  airman's  work  calls  for  more 
or  less  physical  strain  under  conditions  not  encountered  by  land 
athletes,  the  foremost  experts  of  the  country  have  devoted  many 
liours  to  research  work  along  this  line  since  the  war  broke  out.  These 
experts  have  learned  much  and  are  applying  their  knowledge  to  great 
ndvantage.  This  research  has  been  scientific  and  thorough,  and 
thousands  of  individual  cases  where  airmen  have  encountered  diffi- 
culty in  keeping  fit  have  been  studied  minutely  to  ascertain  the  exact 
cause  and  to  determine  the  particular  sort  of  training  necessary. 

391 


392  AIK  SEEVIOE  MEDICAL. 

HIGH  PERSONNEL  STANDARD. 

Naturally  the  men  selected  as  physical  directors  and  commissioned 
in  our  Air  Service  are  men  who  have  had  wide  experience  in  civil 
or  military  life  in  their  respective  lines,  including  both  amateur  and 
professional  athletics.  Trainers  of  college  football,  baseball,  track 
teams,  and  crews;  trainers  of  wrestlers,  pugilists,  big  league  base- 
ball trainers,  gymnasts,  etc.,  were  recruited.  These  men  had  learned 
to  studv  the  human  machine — ^how  to  get  the  most  out  of  it  in  an 
athletic  way,  how  to  detect  the  symptoms  of  "  staleness  "  and  over- 
training, and  also  how  to  keep  the  morale  and  fighting  spirit  of  the 
team  and  the  individual  up  to  the  highest  pitch.  As  far  as  their 
work  with  land  athletes  was  concerned,  the  ability  of  these  trainers 
was  beyond  question. 

Then  came  the  work  of  revealing  to  them  the  physical  problems  of 
the  aviator.  "Air  sickness,"  which  is  pructically  the  same  as  seasick- 
ness on  the  water,  is  something  encountered  by  beginners  in  flying, 
and  this  is  one  of  the  things  which  the  physical  director  learned  that 
he  must  combat.  Tendencies  to  drowsiness  in  the  air  caused  by  the 
singing  of  vibrating  wires  and  the  hum  of  the  motor  had  to  be  coun- 
teracted. The  effect  of  rarefied  atmosphere  at  high  altitudes;  the 
effect  of  aerial  acrobatics  in  which  the  body  is  required  to  go  through 
so  many  unnatural  positions  and  whirled  at  high  speed  in  various 
directions,  which  produces  dizziness.  The  diflSculty  that  flj'ing  men 
in  training  experience  in  obtaining  sufficient  sleep  was  a  topic  for 
study.  Learning  to  differentiate  between  actually  poor  physical 
condition  and  "  ship  shyness,"  a  thing  induced  by  lack  of  confidence 
on  the  part  of  the  individual — all  of  these  were  problems  for  the 
physical  director  as  well  as  the  flight  surgeon.  Thus,  to  the  large 
store  of  knowledge  possessed  b}^  these  physical  trainers  has  been 
added  recently  the  newer  experience  obtained  at  American  flying 
fields.  Of  course,  this  study  will  continue;  new  discoveries  will  be 
made  and  new  methods  adopted. 

The  physical  director  is  immediately  put  under  military  discipline 
as  soon  as  he  enters  the  service  in  order  that  he  may  maintain  disci- 
pline in  accordance  with  military  standards.  He  goes  through  and 
has  to  master  infantry  drill  work  just  like  any  rooky  entering  the 
service  from  civil  life.  He  is  instructed  with  lectures  and  confer- 
ences. His  curriculum  includes  physical  training  courses,  physiologj^ 
infantry  drill,  recreative  games,  disciplinary  drill,  Army  regulations, 
customs  of  the  service,  Army  paper  work,  psychiatry,  cardio- vascular 
system  study  and  other  things  as  well.  From  which  it  will  be  seen 
that  much  is  expected  of  a  director  both  as  a  physical  trainer  and  a 
soldier.    The  interest  of  commanding  officers  in  these  men  is  note- 


o 


3931>-1 


39311-2 


AIR   SERVICE   MEDICAL.  393 

worthy,  for  the  results  which  the  physical  experts  obtain  contribute 
much  to  the  output  of  successful  fliers. 

To  the  credit  of  the  directors  engaged  in  this  work,  it  may  be  said 
without  exception  that  none  of  these  men  was  ever  more  earnest  and 
anxious  to  produce  a  winning  team  on  gridiron  or  track  than  are 
these  same  men  who  are  now  working  with  might  and  main  to  pro- 
duce the  greatest  athletes  of  the  air  to  be  found  among  the  Allies  to 
help  score  the  touchdown  at  the  Berlin  goal  post. 

RIGHT  LIVING  THE  BASIS. 

In  aviation  physical  fitness  is  really  more  necessary  than  in  other 
branches  of  the  service,  in  so  far  as  the  personal  safety  of  the  aviator 
and  the  safety  of  his  plane  are  concerned.  The  soldier  on  land  is  of 
course  at  his  best  when  ph.ysically  O.  K.,  but  he  may  be  below  par 
and  yet  not  show  it,  and  at  the  same  time  he  may  be  in  no  particularly 
great  danger  because  of  this.  That  depends  upon  the  type  of  work  he 
is  doing.  However,  this  is  not  true  of  the  aviator.  He  must  be  right 
at  all  times  or  his  work  will  reveal  his  defects.  If  it  is  not  noticeable 
to  those  watching  him  (as  it  frequently  is),  he  can  not  help  but  be 
conscious  of  it  himself. 

Eight  living  is  the  basis  of  physical  training.  The  cadets  who 
have  had  to  pass  a  most  rigid  test  before  being  accepted  into  the 
service  are  organically  sound  and  none  are  physically  abnormal,  and 
upon  being  inducted  are  constantly  under  the  watchful  eye  of  the 
physical  director,  who  lives,  eats,  and  sleeps  with  the  cadets  and  is 
on  the  lookout  for  symptoms  of  any  disorder.  Therefore  the  physi- 
cal directoi'  need  not  worry  about  the  course  of  strenuous  exercises 
and  flying  calisthenics  being  too  severe  for  the  heart  nor  too  much  of 
a  strain  for  muscles  and  tendons.  With  correct  living  the  correct 
amount  of  sleep  is  obtained — a  minimum  of  7^  or  8  hours.  Cadets 
rise  about  5  a.  m.  and  at  9  p.  m.  they  are  in  bed  (excepting  when  on 
weekly  leave,  when  they  stay  up  later) ,  and  when  "  taps "  comes 
most  of  the  men  are  so  tired  that  they  need  no  coaxing  to  retire. 

Hot  weather  may  make  sleeping  difficult,  especially  in  the  southern 
camps  during  the  summer  months,  where  the  matter  becomes  a 
serious  problem.  It  has  been  found,  however,  that  a  flier  can  not 
keep  fit  without  8  hours  sleep  out  of  the  24.  A  longer  night  period 
of  sleep  than  this  is  conducive  to  laziness  and  is  not  to  be  encouraged, 
although  of  course  it  is  quite  desirable  for  cadets  to  lie  down  for  a 
nap  during  rest  hours,  particularly  when  the  weather  is  warm  and 
sleeping  at  night  difficult. 

When  first  learning  to  fly  the  cadet  may  be  subject  to  air  sickness, 
stomachache,  and  headache,  although  the  new  flying  calisthenics  train- 
ing is  reducing  this  to  a  minimum.     When  such  ailments  occur,  head- 


394  ATE    SERVICE    MEDICAL. 

ache  powders,  laxatives,  and  drugs  of  any  sort  are  not  recommended. 
In  fact,  the  physical  directors  are  very  much  agauist  their  use,  and 
the  flight  surgeons  as  well.  The  regulations  forbidding  the  use  of 
alcohol  in  any  form,  of  course,  eliminate  a  great  deal  of  difficulty 
which  otherwise  might  be  encountered  by  the  director. 

OVEREATING  AND  "  PARTIES." 

Mess  at  the  various  camps  is  prepared  by  competent  cooks  under 
the  direction  of  dieticians,  the  meals  being  scientifically  balanced  so 
that  there  is  no  danger  of  indigestion  or  malnutrition.  Work  in  the 
air  produces  very  keen  appetites,  and  there  is  a  tendency  for  some 
cadets  to  overeat  during  their  first  months  of  training. 

One  of  the  difficulties  encountered  bj?^  the  physical  trainer  is  his 
"blue  Mondays."  In  view  of  the  strenuous  work  the  cadets  are 
obliged  to  do  during  the  week,  it  is  obviously  necessary  to  give  them 
rest  and  recreation  ad  lih.  from  Saturday  afternoon  until  early 
Monday  morning.  Many  of  the  cadets  go  on  week-end  parties,  being 
invited  b}^  friends.  These  well-meanmg  friends  endeavor  to  give 
the  boys  a  good  time,  and  while  there  is  seldom  any  dissipation 
indulged  in,  too  much  to  eat  and  too  rich  foods  do  damage.  At 
(\imp  cadets  are  kept  on  a  regular  simple  diet,  scientifically  prepared. 
They  become  used  to  eating  nourishing  food  and  no  trash.  During 
the  Aveek-end  party  the}^  are  proffered  foods  which  are  not  nourish- 
ing in  nature,  various  dishes  being  quite  indigestible,  and  the  chances 
of  the  cadet  overeating  are  fairly  certain.  Candies  and  ice-cream 
sodas  may  help  to  undo  a  gi-eat  deal  that  the  physical  director  has 
built  up. 

If  well-meaning  friends  of  cadets  could  only  be  induced  to  realize 
that  it  is  a  patriotic  duty  not  to  feed  their  visitors  rich  food  and  too 
much  of  it,  the  physical  director's  task  would  be  easier  and  the 
cadet's  efficiency  and  comfort  oftentimes  would  be  greater. 

EXCESSIVE   SMOKING   TABOO. 

Excessive  smoking  must  be  curtailed.  The  harmful  effect  of  nico- 
tine in  excess  is  quite  noticeable  in  the  men's  work  in  the  air.  Some- 
times because  of  homesiclcness  or  loneliness,  a  cadet  indulges  in 
smoking,  working  perhaps  on  the  assumption  that  it  is  soothing 
and  quieting.  It  is  shortly  noted  by  the  physical  director  that  the 
man's  vitality  is  lowered  and  his  lung  capacity  impaired.  Lung 
capacity  is  vitally  important  for  high  altitude  work.  It  must  be 
developed  at  the  same  time  that  muscles  and  the  sinews  are  being 
developed.  Excessive  smoking  causes  cadets  to  turn  out  of  bed  lieavj' 
of  head,  and  this  in  turn,  together  with  the  lowered  vitality,  causes 
loss  of  enthusiasm  in  their  work  and  has  a  tendency  to  break  down 
the  morale. 


*--v. 


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395b-l 


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H95l>-2 


ATR    SERVICE    MEDICAL.  395 

At  one  of  the  southern  camps  recently  there  was  a  cadet  who  had 
acquired  the  bad  habit  of  smoking  bhick  cigars  both  before  and  after 
mess.  He  had  left  a  Avife  to  whom  he  was  devoted  and  a  small  child 
at  home,  and  frequently  thought  of  his  family  and  found  solace  in 
his  cigars.  That  it  w^as  very  bad  for  him  physically  was  proved 
when  one  day  he  became  befuddled  in  the  air  upon  getting  into  a 
tail  spin  and  could  not  think  clearly  or  quickly  enough  to  prevent  a 
crash.  In  fact  numerous  flying  students  have  been  unable  to  get  out 
of  tail  spins,  not  because  they  were  not  properly  instructed,  but 
because  their  vitality  had  been  lowered  from  one  cause  or  another, 
and  upon  finding  themselves  in  a  dizzy  whirl  were  unable  to  secure 
proper  coordination,  with  a  crash  resulting. 

MASS  ATHLETICS  NECESSARY. 

Exercises  must  necessarily  be  arranged  according  to  the  tempera- 
ture and  weather.  Mass  athletics  are  very  much  to  be  desired,  such 
as  soccer,  football,  progressive  leapfrog,  baseball,  push  ball,  basket 
ball,  combined  with  tennis,  handball,  wrestling,  and  boxing.  The 
iatter  is  especially  encouraged  for  the  reason  that  it  is  one  of  thp 
greatest  exercises  for  developing  quickness  of  movement,  alertness 
and  power  to  keep  one's  head  cool  and  his  thoughts  collected.  "  Fite 
nites,"  as  they  are  called,  which  have  been  established  as  weekly  insti- 
tutions at  Camp  Dick,  Dallas,  Tex.,  and  elsewhere,  are  proving  ex- 
cellent forms  of  diversion  for  the  men.  for  these  not  only  develop 
the  fighting  spirit  and  spirit  of  aggressiveness,  but  keep  the  cadets 
interested  in  their  work  and  improve  the  morale. 

FLYING    CALISTHENICS. 

Runners  do  not  train  for  a  race  in  the  same  manner  as  hammer 
throwers;  swimmers  prepare  for  their  supreme  tasks  in  a  manner 
quite  different  from  the  high  jumper.  Athletes  must  be  trained  for 
their  specialty;  their  bodies  must  be  put  in  absolute  physical  trim 
for  the  work  required,  by  exercises  and  training  which  will  develop 
the  muscles  brought  into  play.  Successful  athletic  trainers  system- 
atically lay  out  the  most  beneficial  exercises  for  each  specialty  of 
i.thletic  endeavor,  and  the  success  of  such  intensive  and  specialized 
training  is  universally  aclaiowdedged. 

Flying  is  a  feat  requiring  mental  and  muscular  coordination  best 
found  in  athletes  in  prime  physical  condition,  and  also  in  those  who 
have  developed  a  sense  of  alertness  through  gymnasium  apparatus 
work  and  tumbling.  The  development  of  this  necessary  muscle-men- 
tal coordination,  together  with  prime  physical  condition  from  the 
usual  athletic  sense,  has  been  combined  in  an  athletic  training  course 
for  fliers. 


396  AIR   SERVICE   MEDICAL- 

This  training  has  been  worked  out  in  a  series  of  flying  calisthenics 
which  are  taught  to  flying  cadets  to  train  them  in  advance  for  the 
difficulties  of  the  air — to  fortify  them  against  dizziness.  This  course 
of  exercise  has  been  scientifically  deA'ised  to  cover  every  aerial  re- 
quirement and  actually  fits  a  man  on  the  ground  to  conquer  the  new 
and  disturbing  sensations  a  flier  encounters.  Thus  not  only  his 
bodily  strength  is  built  up,  but  mentally  he  is  stronger  and  more 
confident,  knowing  he  is  prepared  to  resist  the  influence  of  dizziness 
which  is  a  terror  to  some  men  who  are  starting  to  fly — and  by  many 
regarded  with  such  positive  dread  that  their  work  is  affected  with 
proportionate  decrease  in  their  efficiency. 

Equilibrium  as  such,  from  the  aerial  standpoint,  is  not  merely  a 
sense  of  balance,  but  the  ability  of  an  individual  to  accustom  himself 
to  the  unusual  positions  which  would  ordinarily  produce  dizziness, 
nausea  or  air  sickness,  incapacitating  the  flier  by  making  him  lose 
muscular  and  mental  control,  from  which  so  many  crashes  result. 
Those  exercises  so  accustom  the  flier  to  these  unusual  positions  that 
when  in  the  air  they^  do  not  bother  him. 

\  RADICALLY   NEW   CALISTHENICS. 

The  course  in  flying  calisthenics  is  an  adaptation  of  a  certain  por- 
tion of  regular  Army  calisthenics  combined  with  radically  new  move 
ments,  each  of  which  has  its  special  function.  The  matter  of  flying 
calisthenics  is  not  essentially  a  developer  of  muscle,  although  it  does 
this  to  a  large  extent.  The  principle  underlying  it  is  based  on  the 
scientific  development  of  the  flier,  not  as  an  athlete,  but  for  the  co- 
ordination of  his  mental  and  phj'sical  abilities.  It  is  designed  to 
make  more  acute  his  sense  of  direction,  equilibrium  and  muscle  bal- 
ance, and  at  the  same  time  keep  him  in  sound  mental  and  physical 
condition.  It  prevents  his  muscles  from  becoming  soft  and  at  the 
same  time  carefuU}^  avoids  overtraining,  which  would  be  harmful. 
There  has  been  much  scientific  research  along  this  line,  particularly 
regarding  the  muscles  and  tendons  which  are  subject  to  greatest 
stress  while  the  flier  is  in  the  air — muscles  and  sinews  which  in  or- 
dinary land  athletics  would  not  be  subject  to  such  hard  work. 

Beginning  with  a  few  simple  movements  of  the  head  and  shoulders 
to  strengthen  the  neck  and  shoulder  muscles,  which  are  put  undei* 
strain  while  flying,  the  student  is  taken  through  a  course  of  evolu- 
tions which  produce  a  tendency  toward  dizziness  and  later  overcomes 
it  through  practice.  At  the  outset  a  very  few  turns  will  make  a 
cadet  dizzy.  All  of  these  exercises  are  carried  up  to  a  point  where 
dizziness  is  first  noticeable,  and  not  beyond  that.  The  training 
progresses  and  the  turning  movements  are  done  for  longer  periods, 
the  increase  being  very  gradual  from  day  to  day  until  at  the  end  of 


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AIR   SERVICE    MEDICAL.  397 

30  days  or  so  the  cadets  can  do  all  of  these  various  movements  to  a 
fair  extent  without  becoming  dizzy. 

Among  the  movements  which  have  been  scientifically  developed 
are  those  to  accustom  the  cadet  to  the  effect  of  the  tail  spin  and  the 
spinning  nose  dive.  Other  movements  have  been  developed  to  over- 
come the  dizziness  and  "  lost "  feeling  of  the  so-called  Immelman  turn 
and  the  vertical  spiral.  Ordinary  somersaults  and  forward  and  side 
rolls  are  analogous  to  the  loops  done  in  acrobatics.  As  the  instruc- 
tion progresses  in  these  various  movements,  orders  are  given  at  the 
completion  of  the  movement,  such  as  to  take  four  or  eight  steps  for- 
ward or  to  the  right  or  left  flank,  in  order  to  accustom  the  cadet  to  do- 
ing something  definite  immediately  upon  coming  out  of  his  unnatural 
position.  This  is  something  which  requires  mental  and  physical  co- 
ordination, and  is  vital  to  controlling  a  ship  when  coming  out  of  a 
tail  spin  or  one  of  the  other  acrobatic  movements.  Detailed  explana- 
tion of  these  various  movements  follows : 

While,  of  course,  a  cadet  may  find  these  dizziness  exercises  un- 
pleasant at  first  he  will  soon  become  so  used  to  them  that  he  will  not 
mind  it,  just  as  a  sailor  becomes  used  to  the  action  of  a  ship  at  sea. 

The  accompanying  illustrations  show  the  exercises  which  are  de- 
signed for  the  purpose  of  physical  development  and  accustoming  the 
embryo  pilot  to  the  unnatural  positions  which  he  will  encounter 
sooner  or  later  in  flying.  They  are  given  with  regular  calisthenics  to 
put  men  in  the  pink  of  condition  so  essential  to  the  success  of  the 
beginner.  The  entire  series  is  given  moderately  at  first,  the  idea 
being  to  take  the  men  up  to  the  point  where  dizziness  begins.  This 
is  continued  until  they  become  used  to  the  sensation  and  then  is 
gradually  increased  each  week.  This  training  serves  an  additional 
purpose  in  that  it  provides  a  moderate  endurance  test  of  the  men 
each  day,  as  a  man  must  necessarily  be  in  at  leas4  average  physical 
condition,  in  order  to  take  this  work,  just  as  he  should  be  for  flying. 

FLYING   CAXISTHENICS. 

1.  A  primary  exercise  simulating  the  position  of  the  head  in  a  4o-degree  bank. 

No.  1. — Neck  exercise. 

1.  Hands  on  hips. — 2.  Place. — ^3.  Bend  head  to  right  and  left  (forward  and 
back)  alternately  in  4  counts. — i.  In  cadence. — 5.  Exebcise. 

Repeat  6  to  8  times. 

2.  A  primary  exercise  in  changing  the  head  from  its  normal  position  and 
at  the  same  time  developing  the  neck  muscles  which  are  put  to  constant  use 
while  flying. 

No.  2. — Neck  exercise. 

1.  Hands  on  hips. — 2.  Place. — 3.  Rotate  head  in  4  counts. — 1.  In  cadence. — 
5.  ExEKCisE.  Ml)  Head  bent  forward.  (2)  Circle  head  to  right.  (3)  Back 
(eyes  open,  looking  up).     (4)  Left 

Repeat  4  to  8  times. 

1  Position  illustrated. 


398  AIR    SERVICE    MEDICAL. 

3.  The  effect  secured  in  this  exercise  is  similar  to  that  produced  by  ;i  ver- 
tical bank.  This  also  develops  the  abdomen  on  which  such  strenuous  demands 
are  made  in  flying. 

No.   3. — Vertical    hank   exercise. 

1.  Hands  on  hips. — 2.  Place. — 3.  Circle  trunk  to  right  (left). — 4.  In  ca- 
dence.— 5.  Exercise.  (1)  Trunk  full  bent  forward.  (2)  Move  to  right 
side  bend  position.    M3)  To  the  back  bend.     (4)  To  the  left  bend. 

Repeat  3  to  6  times. 

4.  An  exercise  to  overcome  dizziness  by  accustoming  the  student  to  the 
motion  \^hich  produces  it. 

No.   4. — Rotation  head   and   body   exercise. 

1.  Hands  on  hips. — 2.  Place.-^3.  Rotate  to  right  (left). — 4.  Counts. — 5.  In 
cadence. — 6.  Exercise.  (1)  Trunk  full  bend  forward.  ^(2)  Start  to  de- 
scribe a  circle  about  2  feet  in  diameter.  Number  2  position  90  degrees 
to  right  of  number  1  position.  (3)  Ninety  degrees  counterclockwise  from 
number  2.      (4)   Ninety  degrees  counterclockwise  from  number  3. 

Repeat  4  to  8  times. 
^.  An  exercise  planned  to  accustom  the  student  to  the  sensations  derived 

froJTi  an  Immolman  turn. 

No.  5. — Immelman  turn  exercise — A. 

1.    Hands     on     hips.— 2.    Place.— 3.    Backward.— M.    Bend.— 5.    Right      (left) 

(about). — 6.  Face. — 7.  Forward. — 8.  Bend. 

Repeat  3  to  8  times. 

t).  In  a  climbing  spiral  the  head  is  in  a  position  v/hich  produces  dizziness. 
Two  weeks  practice  tends  to  eliminate  this  condition.  It  was  found  easier 
for  the  cadets  to  become  used  to  this  exercise  with  the  finger  in  the  illustrated 
position,  thus  providing  them  with  a  center  about  which  to  turn.  After  the 
second  week  the  exercise  can  be  executed  with  the  hands  on  hips. 

No.  6. — Cliinbiny  spiral  exercise. 

1.  Right  arm  veritcal. — ^  2.  Point. — 3.  Tubn  to  right  about  finger. — 4.  In 
cadence. — 5.  Exercise.  1-2-3-4.  Completing  3  turns  in  12  counts,  immed- 
iately followed  by  4  (to  8)  paces  forward,  in  4  counts.  Halt  in  position  of 
attention  on  sixteenth  or  twentieth  count. 

Repeat  8  to  6  times. 

7.  Students  becoming  used  to  the  position  of  a  spin  which  produces  dizziness 
before  experiencing  one  in  the  air. 

No.  7. — Tail  spin  exercise. — A. 

1.  Hands  on  hips. — 2.  Place. — 3.  To  the  right  (left).— 4.  In  cadence. — 5.  Exer- 
cise. *(1)  Full  trunk  bend,  right  (left)  finger  pointed  to  ground.  (2)  Start 
turning  to  right  (left)  completing  3  turns  in  12  counts,  folloAved  immediately 
by  4  paces  forward,  in  4  counts.  Halt  in  position  of  attention  on  sixteenth 
count. 

Repeat  2  to  4  times. 


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AlK   SERVICE    MEDICAL.  399 

8.  Chaugiug  the  head  from  vertical  to  horizontal  position,  also  exercising 
abdominal  and  back  muscles. 

No.  8. — Half  lunge  exercise. 

1.  Hands  on  hips. — 2.  Place.— 3.  Lunge  to  right  and  left  alternately,  4 
counts. — 4.  In  cadence. — 5.  Exekcise.  *(I)  Half  lunge  to  right,  with  forward 
knee  bent,  touching  toe  with  fingers.  (2)  Back  to  vertical.  (3)  Half  lunge 
to  left,  with  forward  knee  bent,  touching  toe  with  fingers.  (4)  Back  to 
vertical.  •  * 

Repeat  5  to  8  times. 

9.  This  exercise  is  executed  with  rapid  about  faces  during  the  third  and 
fourth  weeks  of  training,  after  the  student  has  become  used  to  No.  7. 

No.  9. — Tail-spin  exercise — B. 

1.  Hands  on  hips.— 2.  Place.  —  3.  Forward.  —  4.'  Henu. — a.  Hight  (left) 
about). — 6.  Face. 

Repeat  3  to  6  times. 

10.  Looping  the  loop  on  the  ground. 

No.  10. — Forward-roll  en^ercise. 

1.  Forward  roll. — 2.  In  cadence. — 3.  Exekcise.  1-2-3-4.  (1)'  Full  knee  l)ent, 
hands  on  ground.  (2)  Head  between  legs.  (3)  Body  forward  by  weight  of 
hips,  grasping  ankles  with  both  hands.     (4)   Snap  to  attention. 

Repeat  3  to  6  times. 

11.  Looping  on  the  ground  in  reverse  direction. 

No.  II. — Boclctvard-roll  exercise. 

1.  Backward  roll. — 2.  In  cadence. — 3.  Exercise.  1-2-3-4.  (1)  Full  knee  bend. 
(2)  Straighten  legs  sharply,  sending  body  horizontally  to  rear.  (3)*  Roll 
over  backward,  head  l)ent  forward,  hands  placed  on  mat  beside  shoulders. 
(4)   Land  on  feet  and  snap  to  attention. 

Repeat  3  to  6  times. 

12.  The  last  part  of  the  physical-training  period  is  devoted  to  snappy  forward, 
backward,  and  slide  rolls,  the  positions  of  which  are  comparable  to  loops. 

Note. — When  cadets  become  used  to  these  exercises,  after  doing  them  in  one 
place,  they  are  given  4  to  8  paces  forward  or  by  right  or  left  flank. 

This  Is  done  for  the  purpose  of  giving  the  men  a  definite  thing  to  do  imme- 
diately after  being  in  unnatural  positions,  requiring  mental-muscular  coordi- 
nation, which  is  so  vital  in  the  control  of  a  ship  when  pulling  out  of  a  tail  spin. 

"  NOTHING  TO  DO  TILL  TO-MORROW  !" 

A  typical  sequence  in  the  progi-essive  training  of  the  cadets  during 
the  day  is  as  follows,  the  object  being  at  all  times  to  promote  accurate 
and  dependable  mental  activity : 

5  a.  m.  Reveille. 

5.15  to  5.30.  Regulation  calisthenics. 
5.30  to  5.45.  Make  up  quarters. 
5.45  to  6.10.  Breakfast. 

1  Position  illustrated. 


400  AEB  SEEVICE   MEDICAL. 

6.20.  Flying  detachment  assembles  for  flying. 

6.30  to  7.30.  Detachment  not  on  flying  list,  scholastic  work,  one  hour. 

7.30  to  8.30.  Gunnery. 

8.30  to  10.  Scholastic  work,  practical  work  on  motors,  aero  repair  work,  etc.       . 

10  to  11.  Flying  calisthenics  and  games. 

11  to  12.  Shower  baths  (enforced)  and  relaxation.  (The  object  of  this  one 
hour  of  relaxation  before  noon  mess  is  to  give  the  exercised  muscles  that  espe- 
cially desirable  period  of  rest  in  which  to  recover.) 

12  m.  Mess. 

Detachments  which  have  been  flying  in  the  morning  have  their  gun- 
nery, scholastic  work,  and  flying  calisthenics  in  the  afternoon  in  ap- 
proximately the  same  relative  periods. 

6  p.  m.  Mess  and  recreation. 

7  p.  m  Evening  athletics,  such  as  basket  ball,  squash,  tennis,  and  mass  ath- 
letics, intersquadron  baseball  games,  etc. 

In  addition  to  regular  calisthenics  and  flying  calisthenics,  and 
athletic  diversion,  work  on  gymnasium  apparatus  is  very  desirable  as 
a  supplementary  course.  Horizontal  and  parallel  bars,  rings,  Indian 
clubs,  etc.,  are  to  be  encouraged,  while  tumbling  is  especially  valuable 
in  view  of  the  fact  that  in  it  the  tumbler  simulates  positions  he  will 
have  to  assume  in  acrobatic  flying.  This  also  gives  exceptional 
development  of  muscle  balance.  Successful  tumbling  requires  that 
the  student  know  just  where  he  is  in  the  air  during  every  fraction 
of  a  second  required  for  the  movement. 

FREQUENT    RECUPERATIVE    FURLOUGHS    RECOMMENDED. 

The  men  intrusted  with  the  physical  welfare  of  fliers  are  learning 
that  furloughs  and  vacations  are  more  necessary  for  air  men  than 
for  men  in  other  branches  of  the  service,  and  also  should  be  given 
at  more  frequent  intervals.  The  reason  is  that  flying  is  such  highly 
specialized  work  and  inclined  to  produce  nerve  strain  and  "  stale- 
ness."  This  is  particularly  true  when  a  man  has  learned  the  rudi- 
ments of  flying  and  has  been  in  the  air  for  20  hours  or  so.  At  this 
stage  he  is  called  upon  to  fly  day  after  day,  circling  in  ovals  above 
his  field,  and  this  becomes  just  as  tiresome  as  riding  a  bicycle  around 
the  block.  He  craves  cross-country  fl3^ing  and  acrobatics,  and  yet 
is  not  quite  ready  for  this  work.  As  a  result  he  may  suddenly  grow 
stale.  In  fact,  if  he  does  not  he  is  an  exception,  and  when  the  symp- 
toms are  noticed  he  should  immediately  be  given  a  furlough  for  com- 
plete rest. 

There  is  no  doubt  that  the  excessive  heat  of  the  southern  camp  in 
smnmer  induces  staleness,  and  there  is  danger  at  times  of  heat  pros- 
trations or  general  physical  breakdown  resulting.  The  Germans 
have  found  the  value  of  frequent  furloughs.  The  late  Baron  von 
Kichthofen  advocated  it.  In  the  French  Flying  Corps  "aces"  are 
usually  permitted  to  take  a  "permission,"  as  it  is  called,  each  time 


AIE  SEBVICE    MEDICAL.  401 

they  bag  an  enemy  flier,  and  those  who  are  not  aces  receive  such 
permission  ahnost  as  frequently.  This  is  not  altogether  a  means  of 
reward  for  the  fliers,  although  the  French  Army  idolizes  its  flying 
men,  including  its  native  sons,  Americans  and  others  of  the  foreign 
legion  as  well.  The  idea  is  essentially  to  prevent  these  very  skilled 
and  experienced  men  from  growing  stale. 

The  fact  that  the  United  States  Army  Air  Service  training  is 
such  an  intensive  one  and  the  discipline  so  rigid,  means  that  our 
pilots,  both  in  training  and  finished  fliers,  must  have  rest  periods. 

WANTED SWIMMING  POOLS. 

There  is  one  special  crying  need  at  the  southern  aviation  camps, 
a  need  which  fortunately  is  to  be  furnished  in  the  near  future.  We 
refer  to  swimming  pools.  Various  patriotic  contributors  are  inter- 
ested in  the  project  of  providing  pools  for  the  southern  flying  fields 
which  are  unbearably  hot  much  of  the  summer.  The  athletic  train- 
ing for  aviators  to  make  them  fit  for  the  strain  of  flying  must  neces- 
sarily be  carried  to  a  certain  point  even  though  weather  conditions 
are  unfavorable,  and  without  swimming  pools  it  has  been  impossible 
to  make  this  training  anything  like  as  efficient  as  it  could  be  made. 
This  is  particularly  true  of  camps  where  the  temperature  ranges 
from  90  to  120  degrees,  and  where  the  nights  are  so  hot  that  flying 
students  have  difficulty  in  obtaining  the  very  necessary  sleep  which 
they  require. 

When  temperatures  are  as  high  as  this  ordinary  athletics  and 
games  can  not  be  indulged  in  to  such  a  vigorous  extent  as  normally, 
and  swimming,  which  is  splendid  physical  training  in  itself,  is  the 
only  substitute. 

Aside  from  the  refreshing  and  purely  physical  features  of  swim- 
ming, there  is  another  angle  which  is  of  great  importance.  Where 
pools  can  be  maintained  high  diving  and  fancy  diving  must  be 
taught  for  the  reason  that  in  stunt  diving  the  body  is  required  to  go 
through  many  of  the  evolutions  experienced  in  aerial  acrobatics,  and 
furthermore  the  splash  produces  an  effect  upon  the  diver  which  is 
desirable,  for  he  becomes  accustomed  to  keeping  his  thoughts  col- 
lected and  his  head  clear  when  interruptions  in  his  general  trend 
of  activity  occur.  This  is  somewhat  analagous  to  being  in  the  air 
and  suddenly  fired  upon,  in  which  case  the  shock  of  the  surprise 
must  not  affect  the  flier's  efficiency  or  headwork. 

Those  generous  people  who  have  said  to  themselves  "  I  would  like 
to  do  something  substantial  toward  a  healthy  diversion  for  the  boys 
in  aviation  training"  can  find  no  better  answer  than  to  assist  in  the 
project  of  providing  swimming  pools. 

One  needs  but  to  consider  that  after  a  flier  has  been  on  the  flying 
field  from  6  a.  m.  until  noon  in  a  temperature  of  90  to  120  degrees  he 


402  AIE   SERVICE    MEDICAL. 

is  well  heated.  There  is  nothing  in  the  world  that  he  would  rather 
do  than  take  a  shower  or  play  around  in  a  swimming  pool  for  half  an 
hour  before  noon  mess  and  again  late  in  the  afternoon.  At  the 
southern  fields  in  summer  the  cadets  do  not  fl}^  in  the  afternoon  when 
the  temperature  is  high,  and  therefore  have  little  else  to  do  except  to 
fidget  around  in  their  bunks  trying  to  sleep  and  wishing  for  cooler 
weather  and  an  invigorating  swim. 

At  every  flying  field  there  is  a  certain  note  which  permeates  the 
atmosphere — a  note  indicative  of  the  mental  attitude  of  the  men. 
At  some  fields  that  particular  spirit  savors  of  perseverance,  joy,  or 
gloom,  as  the  case  may  be.  The  question  of  morale  is  so  important 
that  officers  can  not  afford  to  neglect  it  in  the  least.  Without  prime 
physical  condition  in  the  men,  high  morale  can  not  be  maintained, 
for  a  sick  body  means  a  sick  mind,  and  a  disordered  mind  means 
grimibling  and  disgruntled  feelings — lowered  morale,  which  mili- 
tates against  the  highest  efficiency  of  the  field. 

The  physical  directors  contribute  perhaps  more  to  the  high 
morale  than  might  be  imagined,  for  it  is  these  directors  who  obtain 
the  confidence  of  the  men  under  them,  engage  in  heart-to-heart  con- 
versations and  listen  to  the  problems  and  petty  difficulties  of  the 
boys  in  a  manner  that  is  not  possible  between  cadets  and  other  offi- 
cers. There  is  a  kinship  existing  between  physical  directors  and  the 
men  under  them — a  kinship  which  is  productive  of  wonderfulh^  valu- 
able results.  These  men  provide  "  snappy,"  "  peppy  "  athletics,  teach 
new  tricks,  show  novel  and  interesting  SAvimming  and  diving  stunts. 
when  swimming  pools  are  available  and  make  the  men  do  something 
which  they  like  to  do — the  ver}^  things  in  the  way  of  diversions  for 
which  the  cadets  pine,  wdien  they  are  on  terra  firma  and  away  from 
their  ships.  Hence,  these  cadets,  possessed  of  enthusiasm  inspired 
by  flying,  find  an  outlet  for  their  enthusiasm  and  can  keep  cheerful. 

Most  of  these  activities  are  on  a  competitive  basis,  providing  the 
true  sporting  element  and  the  men  looking  after  the  bodily  welfare 
of  these  young  soldiers  of  the  air,  are  constantly  so  close  to  their 
charges  and  their  problems  that  the  wisdom  of  the  inauguration  of 
this  new  instruction  is  more  than  commendable.  The  value  of  the 
physical  director  is  incalculable. 

PHYSICAL  TRAINING  FOR   AVIATORS. 

This  special  table  is  published  as  a  guide  to  physical  directors  and 
their  assistants  in  the  training  of  aviators  and  cadets,  and  the  chief 
aim  is  the  procuring  of  the  utmost  activity  of  brain  and.  limb  which 
it  is  possible  to  obtain  in  cadets  taken  in  large  classes  and  without 
proper  clotliiiig  and  apparatus. 


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AIB  SERVICE   MEDICAL.  403 

Any  "  setting-up  "  exercises  should  be  preparatory ;  that  is,  make 
men  ready  for  the  serious  work  of  the  day,  and  in  no  way  exhaust 
any  portion  of  their  vitality. 

Mr.  Walter  Camp  acting  in  an  advisory  capacity,  has  formulated 
12  exercises  which  take  from  12  to  15  minutes  to  execute.  They 
should  not  be  hurried  through,  with  the  idea  of  completing  all  of 
them  in  this  specified  time.  It  is  better  for  the  man  to  master  them 
thoroughly,  using  a  little  more  time  than  to  indifferently  perform 
all  of  them  in  a  hurried,  incorrect  way. 

Not  more  than  an  hour  a  day  will  be  allotted  to  physical  training 
and  every  aviator,  or  cadet,  should  be  exercised  six  days  a  week. 

After  these  12  standard  exercises  have  been  completed,  it  will  be 
left  entirely  to  the  physical  director  as  t®  what  the  balance  of  the 
hour  period  will  be  used  for. 

No  form  of  physical  training  or  running  training  should  be  done 
in  the  early  morning  unless  the  men  have  had  something  substantial 
to  eat,  or  until  half  an  hour  after  breakfast  or  dinner. 

Every  effort  must  be  made  to  organize  the  physical  training  on 
lines  which  will  allow  the  instruction,  once  commenced,  to  continue 
without  interruption  for  one  hour  daily  for  each  cadet. 

Signs  of  abnormal  distress  at  the  conclusion  of  any  physical  exer- 
tion should  be  reported  to  the  flight  surgeon  immediately  by  the 
physical  director. 

It  should  be  remembered  that  this  table  is  not  given  with  the 
view  of  fitting  men  for  the  physical  strain  of  a  football  game  or  a 
long-distance  run,  but  is  designed  to  produce  general  fitness  and  a 
fund  of  vital  resources  in  the  aviator  to  enable  him  to  better  with- 
stand the  peculiar  strain  of  flying. 

STANDARDIZED  TABLE. 

The  physical  director  or  his  assistant  will  name  a  definite  time  for 
each  class  to  be  on  parade.  All  members  of  the  class  should  be  on 
the  gTound  ready  to  fall  in  at  that  time.  Strict  disciplinary  measures 
should  be  taken  with  any  one  arriving  late. 

The  instructor  will  take  up  a  convenient  position,  give  the  com- 
mand "  Fall  in !  "  whereupon  the  class  will  double  to  their  position 
in  two  ranks,  palm  of  left  hand  upon  hip,  the  extreme  right  man  of 
the  front  rank  to  take  a  position  two  paces  directly  in  front  of  and 
facing  the  instructor,  the  right-hand  man  of  the  rear  rank  will  take 
up  his  position  two  full  paces  in  rear  of  this  front-rank  man,  the 
remainder  of  the  class  falling  in  on  the  left  of  these  two  markers.  A 
quick  dressing  by  the  right  should  be  made,  with  alignment  perfect 
and  the  right  arm  of  man  resting  lightly  against  the  left  elbow  of 
the  man  next  on  his  right,  and  then  the  class  stand  at  "  attention." 
89118—19 ^27 


404 


ATB  SERVICE   MEDICAL, 


No  moving,  spitting,  or  talking  should  be  allowed  under  any  circum- 
stances. 

Before  giving  any  lengthy  verbal  instruction,  the  instructor 
should  give  the  command  "Rest."  No  class  should  be  held  in  the 
[Dosition  of"  attention  "  for  any  length  of  time,  neither  should  they  be 
held  in  any  position  of  strain  while  some  movement  is  being  ex- 
plained. 

The  opening  of  ranks,  so  as  to  place  the  class  in  a  position  allowing 
of  the  free  movement  of  arms  and  legs,  will  be  as  laid  down  in  para- 
graph 63  of  the  Manual  of  Drill  Regulations. 

Each  exercise  starts  from  the  position  of  attention.  The  position 
of  attention  will  be  the  same  as  that  for  Infantry  training,  except 
the  fingers  will  be  stretched  straight  down  the  sides  to  their  full 
extent. 

Care  should  be  taken  that  the  breath  is  not  held  while  taking  any 
of  the  following  exercises.  Natural  breathing  is  desirable  through- 
out the  tables  unless  a  breathing  exercise  is  being  given. 

Group  I. 

1,  HANDS. — Arms  CROSS.  (At  arms  cross,  arms  are  exteuded  laterally 
and  horizontally,  palms  down,  lingers  togeMier,  thumb  against  the  forefinger. 
See  figure  2.) 


1.  Hands. 


■3.  Hips. 


Arms  LOWER.  (At  arms  lower,  the  arms  are  brought  back  to  a  position 
of  attention  close  to  the  sides.  See  figure  1.  Especial  care  should  be  taken  to 
see  that  whenever,  throughout  the  exercises,  this  position  is  taken — as  at  the 
completion  of  each  exercise — full  control  is  retained  over  the  arms,  and  the 
hands  should  not  be  allowed  to  slap  against  the  sides  audibly.) 

2.  HIPS.— VHips  FIRM.  (At  hips  firm,  the  hands  are  placed  on  the  hips 
with  shoulders,  elbows,  and  thumbs  well  back.     See  figure  3.) 

Hands  DOWN.  (At  hands  down,  the  arms  are  brought  back  to  a  position 
of  attention  close  to  the  sides.     See  figure  1. ) 

3.  HEAD. — Head,  Ready,  Cross,  ONE.  (At  one,  the  hands  are  placed  be- 
hind the  neck,  index  finger  tips  just  touching,  and  elbows  forced  back.  See 
figure  4.)     TWO.     (Position  of  attention  resumed.)     Rest. 


ALB   SERVICE    MEDICAL. 


405 


The  above  exercises  sh»uld  be  executed  but  a  few  times  eacli,  beini 
paratory  to  tlie  speed  test. 

SPEED  TEST. 


pre- 


In  this,  the  preparatory  command  is  omitted  and  the  instructor  gives  the 
commands,  Hands,  Hips,  Head,  etc,  in  sharp  succession,  varying  them,  and 
occasionally  repeating  a  command  in  a  manner  calculated  to  catch  the  unwary 
napping.  , 

Gboxjp  II. 

1.  GEIND. — Arms  CROSS.     (See  figure  2.) 

Palms  TURN.  (At  turn,  the  palms  are  turned  up  with  badvs  of  hands 
down  and  arms  forced  back  as  far  as  possible.     See  figure  5.) 

Grind,  ONE,  TWO,  THREE,  FOUR,  FIVE  to  TEN.  (At  grind,  and  in 
time  with  the  leader's  measured  counting,  circles  of  12-inch  diameter  are 
described  with  the  finger  tips,  which  move  forward  and  downward,  then  back- 
ward and  upward,  the  arms  remaining  stiff,  and  pivoting  from  the  shoulders. 
On  the  backward  movement  of  the  circle,  the  arms  should  be  forced  back  to 
the  limit.    A  complete  circle  should  be  described  at  each  count. ) 


4.  Head. 


5.  Grind. 


Reverse,  one  to  ten.     (At  reverse,  the  same  process  should  be  gone  through, 
tlie  circles  being  described  in  the  opposite  direction.) 
Arms  LOWER.     (See  figure  1.)     Rest. 
Ten  circles  are  described  in  each  direction. 

2.  GRATE. — Grate,  Ready,  CROSS.  Grate,  one,  two.  (At  grate,  and  as 
the  leader  counts  one,  the  arms  are  slowly  raised,  as  a  deep  inhalation  is 
taken,  to  an  angle  of  45  degrees  from  horizontal,  and  at  the  same  time  the 
heels  are  raised  till  the  weight  of  the  body  rests  on  the  balls  of  the  feet.  See 
figure  6.  At  two,  the  arms  are  returned  to  cross,  as  all  air  is  exhaled,  and  the 
heels  are  lowered  to  a  normal  position.  Care  should  be  taken  to  see  that  the 
arms  are  not  allowed  to  drop  below  the  level  of  the  shoulders  or  to  rise  more 
than  45  degrees.)     Rest. 

The  arms  should  be  raised  and  lowered  10  times. 

3.  GRASP. — Head,  Ready,  CROSS.  (Same  as  4.)  Trunk  Forward, 
BEND.  Upward,  STRETCH.  Backward,  BEND  (slowly).  Upward, 
STRETCH.  (With  head  up  and  eyes  front,  and  at  command  from  instructor, 
the  body  is  bent  forward  from  the^  waist  as  far  as  possible.  See  figure  7. 
The  body  is  returned  to  upright  position  and  at  backward  bend  is  bent  slowly 


406 


AIE   SEBSVICE   MEDICAL. 


as  far  back  as  possible  from  the  waist,  being  returned  to  upright.     Care  should 
be  taken  to  see  that  this  motion  is  sustained  and  not  jerky.)     Best. 
The.  entire  movement  should  be  repeated  five  times. 


6.  Grate,  upper  position. 


7.  Grasp. 


Group  III. 


1.  CRAWL. — Feet  CLOSED,     (Feet  are  closed,  toes  brought  together.) 
Arms  CROSS.     (See  figure  2.) 

CRAWL,  one,  two,  three,  four;  one,  two,  three,  four.  (At  crawl,  the  left 
palm  is  turned  up,  as  the  reader  counts  one,  two,  three,  four,  the  left  arm  is 
raised  and  the  right  arm  lowered  laterally  until  at  four  the  right  arm  should 
be  in  a  position  of  hands,  and  the  left  arm  should  be  extended  straight  up  with 
the  palm  to  the  right.  See  figure  8.  Then,  as  the  leader  counts  one,  two,  three, 
the  body  is  slowly  bent  sidewise  from  the  waist,  the  right  hand  slipping  down 
the  right  leg  to  or  beyond  the  knee,  and  the  left  arm  bending  in  a  half  circle 
over  the  head  until  the  fingers  touch  the  right  ear.  See  figure  9.  At  four  the 
position  of  cross  is  quickly  resumed,  and  as  the  leader  com- 
mences to  count  again  the  right  palm  is  turned  up  and  the 
exercise  completed  in  the  opposite  direction.) 

Arms  LOWER.      Feet  OPEN.      Rest. 
The  entire  movement  should  be  repeated 
five  times. 

3.  CURL. — Left  foot  sideways  PLACE. 
(In  this  movement  at  the  word  place,  the 
left  foot  is  carried  off  about  12  inches  from 
the  right  foot.  The  toes  should  touch  the 
ground  first,  there  being  a  pause  between 
the  toes  touching  the  ground  and  the  heel 
being  lowered.) 

CURL,  one,  two,  three,  four;  one,  two, 
three,  four;  one,  two,  three,  four.  (Ai 
curl,  and  as  the  leader  counts  one,  two, 
three,  four,  the  fists  and  lower  arms  are 
bent  down  from  the  elbows,  which  are  kept 
pressed  back  and  the  fists  are  curled  into 
the  arm  pits.  This  position  should  be  reached  at  three,  when  the  head  and  shoul- 
ders should  be  forced  back  very  strongly,  reaching  the  limit  of  motion  at  four. 
See  figure  10.  The  leader  again  counts  one,  two,  three,  four.  At  one  the  arms 
are  extended  straight  forward  from  the  shoulders,  palms  down.     See  figure  11. 


8.  Crawl,  upright 
position. 


Crawl,  crawl 
positiou. 


Alfi   SERVICE    MEDICAL. 


407 


At  two  the  arms  begin  to  fall  and  the  body  bends  forward  from  the  waist, 
head  up  and  eyes  front,  until,  at  four,  the  body  has  reached  the  limit  of  mo- 
tion and  the  arms  have  passed  the  sides  and  have  been  forced  back  and  (as 
the  trunk  assumes  a  horizontal  position)  up  as  far  as  possible.  See  figure 
18.  (Note  that  in  this  figure  feet  are  together,  which  is  incorrect  for  this  exer- 
cise.) This  is  the  wing  position.  For  a  third  time  the  leader  counts  one,  two, 
three,  four,  as  the  body  is  straightened,  reaching  an  upright  position  with  arms 
straight  forward  at  three.  Cross  is  resumed  at  four.  As  the  body  is  straight- 
ened from  the  wing  position,  a  full  breath  should  lie  taken,  the  lungs  being  lilled 


Fig. 


Curl  position.       Fig.  11. — Curl — Arms  forward.       Fig 


Crouch. 


to  the  maximum  as  cross  is  resumed  at  the  completion  of  the  movement.  This 
breath  should  be  retained  during  the  curl  movement,  and  exhaled  as  the  wing 
position  is  taken.     Inhale  through  the  nose.     Kest. 

The  entire  movement  should  be  repeated  five  times. 

3.  CEOTJCH. — Feet  closed  and  full  OPEN.  (Feet  closed  and  then  opened 
to  90  degrees.) 

Arms  CROSS.     (See  figure  2.) 

On  the  toes  RAISE,  knees  bending.     (Lift  heeis  from  ground.) 

Knees  BEND.  (At  knees  bend,  the  knees  are  bent  and,  with  the  weight  on 
tlie  toes,  the  body  is  lowered  nearly  to  the  heels,  keeping  the  trunk  as  nearly 
erect  as  possible.     See  figure  12.) 

Upward  STRETCH.     (The  upright  position  is  resumed.) 

Heels  LOWER.     (Lower  the  heels  to  ground.) 

Arms  LOWER. 

Feet  close  and  OPEN.  (Feet  closed  and  opened  to  natural  attention  angle 
of  45  degrees.)     Rest. 

The  entire  movement  should  be  repeated  five  times. 

Gboup  IV. 

1.    WAVE. — Feet,      CLOSED.      (Toes 
brought  together.) 

Arms,  BEND.  (Forearm  brought  to 
peipendicuh'.r  position;  fist  closed  and  in 
line  with  the  shoulder,  elbows  well  down.) 

Arms  upward,  STRETCH.  (Arms  are 
stretched  upward.     See  figure  17.) 

Hands,  CLASP.  (The  fingers  interlaced 
and  arms  touching  the  ears.  See  figure 
13.) 


13.  Wave. 


408 


Am  SEEVICE   MEDICAL. 


WAVE,  one,  two,  three,  four.  (Then,  as  the  leader  counts  one,  two,  three, 
four,  a  complete  circle,  of  about  24  inches  diameter,  is  described  with  the 
hands,  the  body  bending  only  at  the  waist  The  trunk  should  be  bent  as  far 
bacliward  as  forward  and  as  far  to  one  side  as  to  the  other.  The  body  should 
be  forward  at  one,  to  the  right  at  two,  bacliward  at  three,  and  to  the  left  at 
four.     The  motion  should  be  steady  and  not  in  jerks.) 

Reverse,  one,  etc.     (At  reverse,  the  same  movement  should  be  repeated  in 
the  opposite  direction,  i.  e.,  to  the  left.) 
Arms,  BEND.     (As  above.) 

Arms  downward,  STRETCH.      (Position  of  attention.) 
Eeet,  OPEN.     (Open  feet  to  angle  of  45°.)     Rest. 
Five  circles  should  be  described  in  each  direction. 
2.  WEAVE. — Arms,  CROSS.     (See  figure  2.) 
Left  foot  sideways,  PLACE.      (In  this  movement  at  the  word 
place  the  left  foot  is  carried  off  about  12  inches  from  the  right  foot. 
The  toes  should  touch  the  ground  first,  thei*e  being  a  pause  between 
the  toes  touching  the  ground  and  the  heel  being  lowered.) 

WEAVE,  one,  two,  three,  four;   one,  two,  three,  four.      (At 

weave,  and  as  the  leader  comits  one,  two,  three,  four,  the  body  is 

I^JjLJ        turned  to  the  left  from  the  hips,  the  arms  maintaining  the  same 

I  i   /         relation  to  the  shoulders  as  at  cross,  until  at  one  the  face  Is  to  the 

left,  the  right  arm  pointing  straight  forward   (in  relation  to  the 

feet)  and  the  left  arm  straight  backward.     See  figure  14,     At  two 

the  body  is  bent  from  the  waist  so  that  the  right  arm  goes  down 

and  the  left  up,  until,  at  three,  the  fingers  of  the  right  hand  touch 

the  ground   midway   between  the  feet.     The  left   arm   should   be 

pointing  straight  up,  with  the  face  still  to  the  left.    The  right  knee 

must  be  slightly  bent  to  accomplish  this  position.     See  figure  15. 

At  four  the  position  of  cross  is  resumed,  and  as  the  leader  again  counts  one, 

two,  three,  four,  the  same  movement  is  repeated,  with  the  left  hand  touching  the 

ground  this  time.     Throughout  the  exercise  care  should  be  taken  that  the  arms 


14.  Weave- 
turn  posi- 
tion. 


17.  Wing— stretch  position. 


15.  Weave — bend  position. 


16.  Weave — combination  turn. 


remain  in  the  same  straight  line,  making  no  separate  movement,  but  changing 
their  position  only  as  the  trunk  and  shoulders  are  moved  and  carry  the  arms 
along.  After  this  exercise  has  been  thoroughly  mastered,  the  turning  and  bend- 
ing movements  made  on  the  counts,  one  and  two,  should  be  combined,  i.  e.. 


AIR  SERVICE   MEDICAL. 


409 


instead  of  makiug  the  entire  turn,  as  described  above,  before  bending,  turn  and 
bend   simultaneously.    See  figure  16.) 

Left  foot  inward,  PLACE.     (Resume  position   of  heels  to- 
gether smartly.) 

Arms,  LOWER.     (iSee  figure  1.)     Rest. 

The  entire  movement  should  bo  repeated  ten  times. 

3.  WING. — Arms,  CROSS.     (See  figure  2.) 

WING,  one,  two,  three,  four;  one,  two,  three,  four.  (At 
wing,  and  as  the  leader  counts  one,  two,  three* four,  the  arms 
are  raised  laterally  until  they  are  extended  straight  upward  at 
one.  See  figure  17.  At  two  the  arms  begin  to  fall  forward  and 
downward  and  the  body  bends  forward  from  the  waist,  head 
up  and  ej'es  front,  until,  at  four,  the  body  has  reached  the  limit 
of  motion  and  the  arms  have  passed  the  sides  and  have  been 
forced  back  and  (as  the  trunk  assumes  a  horizontal  position)  up 
as  far  as  possible.  See  figure  18.  As  the  leader  again  counts 
one,  two,  three,  four,  the  body  is  straightened,  reaching  an  up- 
right position,  with  arms  vertically  extended,  at  three.  At  four 
the  arms  are  lowered  to  a  cross  position,  but  with  palms  up  and  arms  and  shoul- 
ders forced  hard  back.  Very  slow  counting  is  essential  to  the  correct  execution 
of  this  exetcise.  All  air  should  be  forced  fi-om  the  lungs  as  the  body  bends  for- 
ward to  the  wing  position  and  they  should  be  tilled  to  capacity  as  the  body  is 
straigliteued  and  the  arms  brought  down.     Inhale  through  the  nose.) 

Arms,  LOWER.      Rest. 

The  entire  movement  should  be  repeated  five  timesi 


18. 

Wing— wing 
position. 


CHAPTER  X. 
THE  FOOD  PROBLEM  OF  THE  FLIER. 


THE  CARE  OF  THE  FLIER  WITH  REFERENCE  TO  HIS  FOOD. 

As  our  experience  multiplies  we  are  more  and  more  impressed  with 
the  truth  of  the  fact  that  the  flier  is  a  delicately  adjusted  mechanism 
and  that  to  obtain  the  maximum  efficiency  in  that  mechanism  more 
than  the  ordinary  care  must  be  exercised.  Anything  which  disturbs 
either  his  mental  or  physical  equilibrium  serves  also  to  disturb  his 
efficiency.  The  flier  must  not  only  be  given  physical  exercise  to  keep 
his  body  in  condition  but  his  causes  for  worry  must  be  removed ;  he 
must  have  sufficient  rest ;  in  fact,  everything  must  be  done  that  will  in 
any  way  contribute  toward  putting  him  in  perfect  condition  and 
keeping  him  there.  ii 

The  flier  is  subjected  to  gi'eat  strain,  especially  a  mental  one,  during 
flight -and  this  "keyed-up"  nervous  condition  often  leaves  him  in  a 
state  that  is  more  easily  affected  unfavorably  by  his  surroundings 
than  would  be  the  case  with  the  average  able-bodied  nonflier,  or,  in 
fact,  with  the  flier  himself  at  times  when  not  on  flying  duty.  We 
should  not  overlook  the  fact  that  a  flight  of  relatively  short  duration 
in  the  case  of  the  student  flier  may  leave  him  in  a  state  of  extreme 
fatigue,  both  mental  and  physical.  The  writer,  though  not  a  flier, 
has  had  this  experience.  It  was  not  occasioned  by  a  sense  of  fear, 
for  he  had  perfect  confidence  in  his  pilot ;  but  after  one  to  two  hours 
in  the  air,  and  while  the  flight  continued,  he  was  gradually  seized 
with  an  overpowering  sense  of  drowsiness  and  fatigue.  So  intense 
was  this  feeling  that  it  is  doubtful  to  him  whether  even  the  knowledge 
that  an  accident  was  imminent  would  have  served  to  arouse  him  to 
normal  mental  activity.  That  the  student  flier  may  be  seized  with 
a  similar  feeling  is  evidenced  by  cases  such  as  the  following :  A  ship 
was  seen  by  the  tower  observer  to  descend  in  the  distance  to  appar- 
ently a  forced  landing.  Upon  reaching  the  ship,  the  relief  party 
found  it  had  landed  safely,  though  the  flier  could  give  no  very  good 
reason  for  coming  down  and  seemed  confused.  When  found,  however, 
he  was  fast  asleep  in  the  shade  of  a  wing  of  his  ship.  He  complained 
of  feeling  tired.  Numerous  instances  of  this  or  a  similar  character 
are  encountered  on  the  flying  field.  A  similar  strain  and  a  similar 
state  of  resulting  fatigue  may  come  to  the  experienced  flier  during 

411 


412  AIR   SERVICE   MEDICAL. 

flights  of  long  duration,  and  especially  may  this  be  true  of  the  flier 
on  active  duty  at  the  front.  The  difference  between  the  student  flier 
and  the  experienced  flying  officer  is  largely  one  of  degree.  If  either 
man  is  in  anything  short  of  the  finest  physical  condition  at  the  com- 
mencement of  the  flight,  the  state  referred  to  above  will  certainly 
develop  earlier. 

Again,  the  flier  must  rely  for  his  safety  and  efficiency  upon  the 
perfect  coordination  of  action  of  neuro-muscular  mechanisms  within 
his  body.  By  this  we  mean  the  following:  Information  is  constantly 
coming  into  the  brain  centers  from  the  outside  telling  of  our  relations 
to  our  surroundings.  For  example,  they  come  in  through  the  eye, 
through  the  semicircular  canal  apparatus  of  the  internal  ear,  and 
from  sensory  nerve-endings  in  the  muscles,  tendons,  and  joints.  It  is 
through  the  receipt  of  all  these  messages  in  a  continuous  stream  that 
we  are  made  aware  of  changes  in  our  relations  to  our  environment. 
After  the  receipt  of  these  messages  we  make  our  adjustments  to  the 
environment  through  nerve  impulses  that  travel  out  from  the  vari- 
ous nerve  centers  to  the  muscles.  Through  the  constant  regulation  of 
the  relative  degrees  of  contraction  and  relaxation  of  various  muscles 
we  maintain  the  erect  position,  we  walk  or  run,  or  carry  out  other 
activities.  That  the  maintenance  of  the  erect  position,  for  example. 
is  absolutely  dependent  upon  the  constant  control  and  adjustment  of 
muscles  through  the  nervous  system  is  proved  by  the  fact  that  the 
body  becomes  at  once  a  "  helpless  heap  "  after  the  brain  ceases  to 
exercise  its  normal  control,  e.  g.,  after  a  blow  on  the  head.  When 
visual  images  falling  on  the  retina  warn  us  that  we  are  falling  in  a 
certain  direction  we  contract  the  proper  muscles  and  bring  the  body 
again  into  a  position  of  balance.  If  it  is  dark  and  we  are  unable  to 
obtain  visual  images,  we  are  compelled  to  depend  upon  "  signals  "  that 
come  from  the  internal  ear  and  from  the  muscles  and  joints.  If  we 
feel  dizzy,  we  may  usually  find  some  solid  support  till  the  dizziness 
•  passes.  Or  in  the  dark  we  may  use  a  third  leg  (cane)  or  grasp  neigh- 
boring objects,  such  as  railings,  etc.,  to  assist  in  making  the  proper 
adjustments. 

In  the  case  of  the  flier  it  is  impossible  to  use  all  these  neuro- 
muscular mechanisms  and  these  solid  surrounding  objects  in  the 
maintenance  of  equilibrium  in  exactly  the  same  way  the  race  has 
been  wont  to  use  them  through  the  ages  on  the  solid  earth  or  even 
on  the  sea.  Air  is  a  medium  which  the  eye  can  not  see.  Differences 
in  air  density,  in  direction  and  in  speed  of  flow,  are  properties  that 
we  know  the  air  possesses  but  the  flier  is  unable  to  see  these  varia- 
tions as  he  approaches  them.  It  is  only  after  the  wing  has  actually 
struck  a  mass  of  air  of  greater  density  and  the  ship  has  been  veered 
from  her  course  that  he  learns  of  the  presence  of  the  denser  air. 
His  problem  is  now  to  return  the  ship  to  her  former  course.     He 


^  AIR   SERVICE    MEDICAL,  413 

can  not,  especially  in  night  flying,  depend  upon  the  sight  of  sur- 
rounding objects  in  making  the  adjustment,  but  must  rely  upon  those 
impulses  that  come  in  from  other  than  visual  or  contact  (touch) 
sources  and  his  dependence  upon  them  is  much  greater  than  would 
be  the  case  upon  the  ground.  Experiments  have  shown  that  those 
nerve  impulses  coming  in  to  the  central  nervous  system  from  the 
internal  ear  and  from  muscles  and  joints  are  less  definite  than  those 
that  come  in  through  the  eye,  and  that  cbnsequenlly  it  is  harder  to 
maintain  perfect  equilibrium  when  visual  impulses  are  removed.  The 
flier,  therefore,  has  a  more  difficult  task  to  perform  in  stunt  or  in 
night  flying  than  if  he  were  on  the  ground.  Everything — his  life, 
the  return  of  his  photographs  or  other  information — depends  upon 
the  perfect  coordination  between  the  neuro-muscular  mechanisms 
referred  to  above.  If  he  loses  his  sense  of  direction,  becomes  dizzy 
or  otherwise  mentally  confused,  he  loses  the  mastery  of  his  ship 
to  just  that  extent.  Unless  control  is  regained  through  them  the 
consequences  are  certain. 

Among  those  things  that  may  affect  the  delicacy  of  adjustment 
and  therefore  the  efficiency  of  the  flier  there  is  probably  no  one  thing 
more  important  than  his  food.  It  is  a  matter  of  common  knowledge 
ihat  improper  food,  along  with  constipation,  tend  to  produce  defi- 
ciencies both  mental  and  physical.  Some  of  these  deficiencies  are 
visible  while  others  are  invisible.  We  may  be  able  to  see  the  effects  of 
dizziness,  of  headache,  and  of  mental  sluggishness,  but  there  are 
deficiencies  that  can  not  be  seen  by  the  eye  that  are  none  the  less 
potent;  for  example,  a  decrease  in  mental  acuity  or  of  judgment 
that  might  be  elicited  only  at  the  time  of  an  emergency. 

The  flying  instructor  who  has  had  considerable  experience  knows 
it  is  not  safe  for  a  man  to  go  aloft  if  he  is  not  feeling  "  fit ''  and  will 
advise  such  men  to  stay  on  the  ground.  To  go  aloft  at  such  times 
is  extremely  dangerous  for  the  student  flier  or  the  experienced  officer 
alike.  Only  recently  an  officer,  one  of  the  best  fliers  at  a  certain  post, 
remarked  before  leaving  the  ground  that  he  did  not  feel  exactly  fit. 
Upon  being  told  by  the  officer  in  charge  that  he  had  better  not  go 
up,  he  turned  the  suggestion  aside  with  the  reply :  "  Oh,  it  isn't  as 
bad  as  that.  I  merely  must  have  eaten  something  that  hasn't  agreed 
with  me."  He  went  up.  When  he  came  down,  he  crashed  and  was 
killed.  Such  illustrations  are  all  too  numerous.  We  must  not  over- 
look the  great  importance  of  supplying  all  fliers  with  the  proper 
food.  This  does  not  mean  that  we  should  stop  after  seeing  that  his 
mess  is  provided  with  food  of  good  quality,  nor  even  after  seeing 
that  it  is  well  prepared.  The  flier,  like  all  other  men,  is  a  composite 
of  many  variables.  What  he  is  able  to  eat  at  one  time  may  be  en- 
tirely improper  at  another.'  He  is,  therefore,  in  need  of  at  least  a 
certain  amount  of  individual  attention — certainly  is  this  true  when 


414  AIE  SERVICE   MEDICAL.  I 

he  shows  the  least  signs  of  being  "  unfit."    He  should  not  be  left  at 
such  times  to  the  "  mercies  "  of  the  average  Army  mess. 

In  civilian  life  it  has  been  thought  necessary  to  provide  for  cer- 
tain athletes  a  special  table — ^the  so-called  "  training  table."  Only 
the  best  foods  were  allowed.  Some  were  forbidden  altogether  be- 
cause they  might  reduce  the  efficiency  of  the  human  "  machines  "  of 
the  team.  It  is  true  that  there  is  a  distinct  difference  between  the 
demands  these  athletes  on  the  one  hand,  and  the  flier  on  the  other 
must  meet,  but  let  us  see  wherein  this  difference  lies.  The  athlete 
must  build  up  a  muscular  apparatus  of  the  best  and  strongest  type 
and  must  eat  nothing  that  would  tend  to  interfere  with  its  action. 

The  flier,  however,  is  not  to  engage  in  strenuous  muscular  work; 
his  effort  is"  a  mental  one.  He  must  not  only  be  able  to  apply  the 
maximum  of  clear  judgment,  swiftness  of  thought  and  muscular 
control  at  the  proper  moment,  but  must  have  a  central  nervous 
system  that  can  use  accurately  and  without  dizziness  or  other  defect 
those  impulses  that  were  referred  to  above,  and  that  are  constantly 
streaming  in  from  points  outside  the  central  nervous  system.  Only 
through  the  perfect  control  of  all  of  these  faculties  may  he  hope  to 
achieve  the  maximum  of  success. 

In  the  body  the  most  highly  differentiated  tissue  is  that  composing 
the  nervous  system.  Improper  food  or  feeding  will  affect  the  effi- 
ciency of  the  most  highly  differentiated  tissues  first.  It  is  still  pos- 
sible to  obtain  a  fair  amount  of  work  from  muscles  when  the  higher 
brain  centers  have  become  relatively  inactive.  Inasmuch,  then,  as 
the  fliers'  work  is  mental  rather  than  physical,  and  the  nervous  sys- 
tem is  more  susceptible  to  the  effects  of  improper  food  and  feeding 
than  the  muscular  system,  it  would  seem  to  be  even  more  essential 
that  our  student  and  officer  fliers  be  provided  with  some  form  of 
training-table.  The  training-table  idea  arose  during  peace  times  from 
the  deliberate  judgment  that  it  would  improve  the  physique  of  athlete^s 
and  increase  their  chances  of  winning  in  athletic  games.  That  im- 
provement really  resulted  from  the  use  of  the  training-table  can 
scarcely  be  doubted.  We  wish  to  point  out,  however,  that  the  goal 
aimed  at  was  in  no  sense  as  serious  or  "as  important  as  that  of  the 
flier,  for  in  the  case  of  the  latter,  we  are  concerned  with  the  necessity 
for  every  ounce  of  efficiency  that  can  be  obtained  in  order  to  win  the 
war  with  as  little  delay  and  loss  of  life  as  possible. 

There  should  be  provided  for  every  aviation  camp  a  nutrition  of- 
ficer. This  officer  should  be  especially  well  trained  in  the  knowledge 
of  food  values  in  their  relation  to  the  body,  and  the  more  difficult 
problems  that  arise  from  time  to  time  relating  to  foods  should  be 
referred  to  him.  He  should  work  hand  in  hand  with  the  flight  sur- 
geon and  the  physical  director,  and  these  three  men  together  should 
exert  a  powerful  influence  in  every  camp.    Through  the  flight  surgeon 


AIR  SERVICE   MEDICAL.  415 

the  nutrition  officer  could  establish  close  contact  with  the  physical 
condition  of  the  fliers.  He  should  know  not  only  of  those  who  were 
sufficiently  indisposed  to  report  at  sick  call,  but  also  of  those  who 
show  the  slightest  derangement  of  the  digestive  tract,  and  all  these 
men  should  constitute  for  him  a  special  problem  to  be  worked  out 
in  conjunction  with  the  flight  surgeon  and  the  physical  director  on 
the  one  hand  and  with  the  mess  sergeant  of.  the  cadet  or  officers'  mess 
on  the  other.  The  flight  surgeon  after  discovering,  for  example, 
that  a  given  flier  was  out  of  condition  with  perhaps  constipation, 
headache,  or  other  early  sign  of  digestive  derangement,  would  report 
him  to  the  nutrition  officer.  For  a  period  of  possibly  one  or  two 
meals  the  flier  might  be  required  to  fast  during  purgation  or  other 
treatment  by  the  flight  surgeon,  after  which,  under  the  personal 
supervision  of  the  nutrition  officer,  he  might  begin  to  eat  again — but 
only  those  things  that  were  prescribed  for  him.  There  might  well 
be  one  or  two  tables  in  the  mess  at  which  only  the  men  under  observa- 
tion should  eat.  In  the  meantime  the  physical  director  would  have 
looked  after  the  physical  requirements  of  the  "patient,"  giving 
him  such  exercise  as  he  deemed  best.  During  this  period  and  until 
the  flier  was  pronounced  "  fit "  he  should  be  under  orders  to  stay  on 
the  ground.  There  can  be  little  doubt  that  through  this  active  coop- 
eration of  the  three  men  in  charge  of  the  welfare  of  the  flier  the 
aggi-egate  number  of  hours  lost  per  month  by  the  fliers  on  account  of 
physical  disability  would  be  greatly  reduced,  for  the  average  indi- 
vidual suffering  from  such  complaints  is  inclined  to  let  matters  take 
their  course  and  simply  "wear  it  off."  What  he  needs  is  prompt 
vigorous  attention  from  all  the  angles  mentioned  above.  By  far 
more  important  than  the  foregoing  advantage  of  an  increase  in  the 
number  of  effective  hours,  however,  is  the  fact  that  through  this  type 
of  ser\^ce  the  safety  of  a  very  large  number  of  men  and  ships  would 
be  greatly  increased.  The  actual  expense  involved  in  the  assignment 
of  a  nutrition  officer  to  each  camp  for  this  purpose  would  be  entirely 
out  of  proportion  to  the  benefits  derived  therefrom.  In  proof  of 
this  statement  we  need  onl}?-  mention  the  fact  that  each  finished  flier 
has  been  estimated  to  represent  an  expenditure  by  the  Government 
of  not  far  from  $40,000.  A  nutrition  officer  of  the  rank  of  captain 
in  each  of  the  aviation  camps  in  the  United  States  would  represent 
an  expenditure  each  month  of  only  one-eighth  the  cost  of  training  a 
single  aviator.  If  the  lives  of  only  two  fliers  were  saved  per  year 
throughout  the  United  States  there  would  be  saved  more  than  the  pay 
of  the  whole  force  of  nutrition  officers.  We  have  no  means  of  deter- 
mining at  present  what  proportion  of  accidents  either  fatal  or  non- 
fatal are  due  to  the  lack  of  a  proper  supervision  of  the  food  and  the 
needs  of  the  individual  flier,  but  the  evidence  is  not  lacking  that  this 


416  AIB   SERVICE   MEDICAL. 

factor  is  a  most  important  one.  When  the  greatest  speed  in  the 
development  of  our  air  resources  is  so  essential  to  success,  we  can  ill 
afford  to  neglect  this  important  side  of  the  care  of  the  flier.  This 
would  still  be  true  though  the  cost  of  that  supervision  were  many 
times  what  it  would  be  through  the  provision  of  nutrition  officers. 

The  need  for  trained  supervision  of  fliers'  messes  is  of  the  greatest 
importance  from  entirely  a  difi'erent  angle  and  for  several  reasons: 
First,  the  student  flier  has  been  grouped  in  the  aviation  camp  for 
purp£)ses  of  instruction  and  messing  into  what  resembles  superfi- 
cially a  squadron.  The  men  meet  together  in  classes,  eat  together, 
sleep  and  drill  together,  as  do  the  squadrons,  but  here  the  similarity 
ceases.  Unlike  the  men  in  the  squadrons,  they  are  present  as  indi- 
viduals, they  arrive  at  the  post  individually  or  in  small  groups,  com- 
plete their  instruction,  and  leave  as  individuals.  While  they  are  in 
the  camp  they  have  but  one  object,  namely,  to  learn  to  fly.  It  is 
impossible  to  detail  any  cadet  to  serve  as  cook,  as  this  would  practi- 
cally stop  his  flying  instruction.  Cooks  for  these  men  must  there- 
fore be  obtained  from  some  source  outside  the  cadet  organiza- 
tion. The  problem  of  obtaining  a  sufficient  number  of  well-trained 
cooks  for  our  Army  messes  has  been  and  still  is  a  tremendous  one. 
This  is  easily  understood  when  we  recall  the  fact  that  not  far  from 
40,000  cooks  are  required  for  each  1,000,000  soldiers ;  that  is,  a  total 
of  200,000  for  an  Army  of  5,000,000  men.  In  various  camps  different 
plans  have  been  tried  for  the  operation  of  cadet  messes.  In  some  of 
them  colored  civilian  co,oks  were  used ;  in  others  white  civilian  cooks ; 
in  still  others  enlisted  cooks  from  the  squadrons  at  the  post  were 
detailed;  and  finally  in  others  a  combination  of  enlisted  and 
white  civilian  cooks  was  tried.  In  a  majority  of  instances 'condi- 
tions in  these  messes  were  found  to  be  unsatisfactory;  in  some  of 
them,  especially  where  colored  help  was  used,  extremely  so.  This 
■v^  as  true  not  only  from  the  sanitary  standpoint,  but  from  the  stand- 
points of  methods  of  food  preparation  and  of  food  wastage.  The 
question  of  the  provision  of  an  adequate  mess  force  for  such  messes 
will  be  taken  up  a  little  later.  Until  such  an  adequate  mess  force 
has  been  provided  for  every  cadet  mess,  however,  the  need  for 
constant  supervision  by  a  nutrition  officer  will  be  doubly  important. 

Second,  the  flying  officers  in  most  camps  take  their  meals  at  the 
officers'  mess,  and  in  many  instances  the  officers'  mess  has  been  found 
to  be  unquestionably  the  worst  one  on  the  post.  In  the  matter  of  the 
commissioned  officers'  mass  we  are,  it  is  true,  confronted  with  an 
established  Army  usage  under  which  the  officers  are  required  to 
conduct  their  own  mess.  This  has  been  and  is  in  line  with  the 
requirement  that  the  officer  shall  provide  for  himself  both  food  and 
clothing.  Since,  however,  the  Government  is  so  vitally  interested 
in  the  welfare  of  the  flier  as  it  may  be  affected  by  his  food,  it  would 


AIR   SERVICE   MEDICAL.  417 

seem  essential  that  at  least  a  certain  amount  of  supervision  of  the 
officers'  mess  should  be  exercised.  It  is  our  belief,  ivpui  experience 
in  the  field,  that  there  would  result  no  serious  difficulty  among  the 
officers  themselves  if  the  nutrition  officer  were  to  supervise  the  menus 
of  these  messes — if  in  fact  he  were  to  exercise  the  same  close  super- 
vision over  the  food  of  each  flying  officer  as  over  that  of  the  flying 
cadet.  This  supervision  should  be  carrie^d  out  in  the  case  of  the 
officer,  as  in  that  of  the  cadet,  through  cooperation  with  the  flight 
surgeon  and  physical  director. 

There  are  three  messes  in  every  aviation  camp,  namely,  the  cadet 
mess,  officers'  mess,  and  post  hospital  mess,  which  are  different  in 
o)ie  respect  from  all  squadron  messes.  In  these  three  messes  the 
cooks  occupy  a  permanent  position.  They  do  not  move  on  with  their 
organization,  since  these  organizations  never  move;  moreover,  in 
all  three  of  them  we  require  the  best  cooks  obtainable.  To  supply 
these  messes  with  a  proper  cooking  force  would  require  for  our 
aviation  camps  alone  approximately  500  men.  This  means  the  per- 
manent sidetracking  in  the  United  States  of  500  of  our  best  enlisted 
cooks.  We  have  advocated  elsewhere  for  all  these  messes  the  use  of 
carefully  selected,  properly  qualified,  women  cooks  in  order  that  the 
500  enlisted  cooks,  of  which  there  is  such  an  acute  shortage,  might 
be  freed  for  overseas  service  in  hospital  and  fliers'  messes.  In  a  matter 
as  important  as  the  food  supply  we  surely  can  not  afford  to  provide 
anything  less  than  the  best  of  cooks  for  either  the  cadet,  flying  officer, 
or  hospital  patients'  messes,  and  on  account  of  the  shortage  of  cooks 
with  which  we  are  confronted,  the  substitution  of  women  for  enlisted 
men  in  the  United  States  is  highly  desirable.  The  extension  of  the 
conscription  ages  to  include  those  18  to  45  years  of  age  will  greatly 
increase  the  problem  of  obtaining  good  male  civilian  cooks  in  any  of 
these  messes,  for  not  only  Avill  there  be  a  scarcity  of  men  but  an 
increase  in  the  wage  demanded  as  well. 

A  large  part  of  the  time  of  the  nutrition  officer  would  be  devoted 
to  the  care  of  the  cadets'  and  officers'  messes,  but  by  no  means  all  of 
it  should  be  devoted  to  them.  The  nutrition  officer  should  be  charged 
not  only  with  the  duty  of  providing  a  proper  menu  for  the  fliers  and 
studying  the  individual  needs  of  these  men,  but  should  have  general 
supervision  of  all  food  problems  in  every  mess  at  the  post.  These 
latter  should  include  a  supervision  of  the  food  as  to  quality  when 
received  by  the  messes;  recognition  of  the  early  signs  of  spoilage 
so  as  to  prevent  the  use  of  food  imfit  for  use;  the  character  of  the 
menus;  the  conservation  of  foods;  the  proper  refrigeration  of  foods 
in  the  mess;  the  sanitary  side  of  food  handling;  in  short,  he  should 
be  in  charge  of  food  problems  from  absolutely  every  angle.  There 
are  many  difficult  problems  that  arise  constantly  in  the  messes,  and 
it  is  not  sufficient  to  provide  men  for  the  mess  who  know  simply  how 


418  AIE  SERVICE   MEDICAL. 

to  concoct  dishes.  The  services  of  a  man  who  has  had  special  train- 
ing are  required.  This  is  true  of  aviation  camps  to  an  extent  that 
is  even  greater,  perhaps,  than  it  is  of  the  large  cantonments,  for  the 
reason  that  the  large  cantonments  have  a  large  medical  staff  and  a 
well-trained  sanitary  inspector.  Among  them  will  usually  be  found 
some  one  who  is  capable  of  handling  most  problems  that  arise.  In 
the  small,  relatively  isolated  aviation  camps,  on  the  other  hand, 
there  are  very  few  medical  men,  and  it  often  happens  that  there  is 
no  one  at  hand  who  can  handle  such  problems,  with  the  result  that 
they  are  either  poorly  handled  or  allowed  to  persist  indefinitely. 
Experience  in  the  field  has  shown  that  these  unsatisfactory  condi- 
tions, where  they  exist,  are  seldom  due  to  a  lack  of  interest  on  the 
part  of  the  men.  They  are  due  rather  to  the  fact  that  we  have  sud- 
denly assembled  a  large  group  of  men  who  find  themselves  con- 
fronted with  problems  outside  their  realm  of  experience.  The  re- 
markable thing  about  it  all  is  that  the  messes  have  done  as  well  as 
they  have,  and  not  that  they  have  problems  that  are  seriously  in 
need  of  attention  by  men  with  special  training. 

Under  the  direction  of  the  nutrition  officer  the  mess  forces  of  all 
messes  at  the  post  could  receive  instruction  along  those  lines  men- 
tioned above;  they  could  be  taught  what  we  mean  by  the  balanced 
ration ;  how  to  make  up  a  menu  so  that  it  would  fill  the  requirements 
of  the  balanced  ration ;  how  to  care  for  the  mess  equipment ;  how  to 
handle  the  mess  force  to  the  best  advantage  so  as  to  get  the  best 
results;  how  to  use  left-overs;  how  to  prevent  the  production  of 
left-over  food ;  how  to  store  foods  to  prevent  undue  wastage ;  how  to 
keep  a  proper  accoimting  system,  without  which  no  mess  can  be 
operated  with  the  best  success.  Only  the  mess  in  which  the  exact 
state  of  the  mess  fund  is  known  each  day  can  be  operated  with  the 
maximum  efficiency.  Through  the  cooperation,  constant  supervision, 
and  encouragement  of  the  mess  officer  the  mess  forces  throughout  the 
post  could  be  raised  in  a  relatively  short  time  to  a  high  state  of 
efficienc,y  and  kept  there.  It  is  not  sufficient  to  send  a  nutrition  officer 
to  the  post  for  a  brief  time  and  then  transfer  him  to  another  post. 
There  is  too  great  a  tendency  for  the  men  to  return  to  old  habits 
unless  there  is  constant  supervision,  and  there  rarely  is  anyone  on 
the  medical  staff  of  the  post  hospital  who  is  qualified  to  follow  up 
the  work  of  the  nutrition  officer.  Especially  is  this  true  of  the  type 
of  care  that  the  student  and  officer  flier  should  have. 

The  cooking  forces  in  aviation  camp  messes  are  particularly  in 
need  of  both  the  training  mentioned  above  and  of  constant  supervi- 
sion for  a  long  time  after  receiving  this  training,  because,  in  the  vast 
majority  of  cases,  they  have  never  had  the  advantage  of  training  in 
the  cooks'  and  bakers'  school.  There  has  been  an  authorization  under 
which  commanding  officers  could  detail  cooks  from  the  squadrons 


AIR  SERVICE   MEDICAL.  419 

to  attend  this  school,  but  in  practice  there  has  rarely  been  an  oppor- 
tunity to  take  advantage  of  it.  The  squadrons  have  been  so  short  of 
men  that  it  has  been  impossible  in  most  cases  to  spare  anyone  long 
enough  to  permit  attendance  at  the  cooks'  and  bakers'  school.  Con- 
sequently the  men  have  been  forced  to  rely  upon  their  own  resources. 
In  general,  they  have  been  remarkably  successful — some  of  them,  of 
course,  more  so  than  others — but  all  are  in  need  of  just  such  assist- 
ance as  could  be  obtained  from  the  continued  presence  of  a  nutrition 
officer  at  the  post. 

In  order  to  bring  out  more  clearly  the  exact  nature  of  the  problems 
that  are  constantly  arising  in  the  messes,  and  that  demand  the  super- 
vision of  an  experienced  man,  we  will  state  a  few  of  them  a  little 
more  in  detail. 

First,  the  quality  of  the  foods.  For  the  most  part  the  foods  sup- 
plied to  the  messes  by  the  Quartermaster  Department  are  of  excel- 
lent quality.  It  is  quite  necessary,  how^ever,  not  only  to  be  able  to 
recognize  the  early  signs  of  spoilage  in  various  foods  but  to  be  con- 
stantly on  the  watch  for  such  spoilage.  Some  spoiled  food  may 
occasionally  come  along  with  the  fresh  supply,  or  food  that  was  of 
good  quality  when  received  may  spoil  before  being  used.  This  is 
especially  true  in  the  southern  camps  during  the  long  hot  smnmer 
months.  Again,  spoilage  is  very  likely  indeed,  to  be  found  in 
foods  purchased  from  extra  quartermaster  sources,  and  during  the 
summer  season  there  is  a  large  purchase  of  these  fresh  garden  foods. 

It  is  necessary  for  the  mess  force  to  be  able  to  recognize  "  specifi- 
cation beef" — that  is,  beef  that  has  been  cut  according  to  the 
"Army  trim  "  method  rather  than  the  ordinary  "  commercial  cut " ; 
also  differences  in  sex,  age,  and  quality  of  the  beef.  This  knowledge 
is  especially  necesary  in  the  aviation  camps,  since  some  of  them  are 
located  poorly  with  regard  to  markets  and  frequently  are  unable  to 
buy  to  advantage.  If  the  mess  force  knows  what  constitutes  "  speci- 
fication beef  "  it  is  much  easier  to  control  the  supply.  The  Quarter- 
master contracts  for  neither  cow  nor  bull  beef,  nor  for  even  the 
cheaper  cuts  of  the  steer  quarter,  such,  for  example,  as  the  neck, 
kidney  fat,  hock  joints,  and  hanging  tenderloin.  It  is  very  im- 
portant that  the  cooks  be  able  to  recognize  the  early  signs  of  spoilage 
in  beef,  and  especially  that  they  be  able  to  determine  the  extent  of 
any  spoilage  that  is  present.  It  is  fully  as  important  for  them  to 
know  when  to  trim  away  small  surface  areas  that  smell  badly  and 
use  the  remainder  of  the  quarter  (provided  spoilage  has  been 
limited  practically  to  the  surface)  as  to  know  when  to  throw  away 
the  whole  quarter.  It  has  happened  too  frequently  that  inexperi- 
enced cooks  have  asked  to  have  a  quarter  of  beef  condemned  when 
the  trimming  off  of  one  or  two  pounds  from  certain  points  removed 
all  that  showed  the  least  sign  of  beginning  spoilage.  In  such  cases 
89118—19 28 


420  AIE  SERVICE   MEDICAL. 

the  condemnation  of  the  whole  quarter  would  have  been  an  unpar- 
donable waste.  The  caution  displayed  by  the  cooks,  in  such  in- 
stances, is  laudable  for,  after  all,  they  are  responsible  for  the 
quality  of  food  they  serve  in  their  mess.  It  is  only  necessary  to 
train  them.  Experience  shows  that  this  training  is  difficult  and 
requires  considerable  time.  We  can  not  afford  to  furnish  a  Federal 
meat  inspector  for  each  of  these  small  posts,  but,  after  all,  it  is 
unnecessary  for  this  is  one  of  the  things  a  nutrition  officer  would 
take  over  and  handle  among  the  many  other  services  he  would 
render  the  camp. 

The  above  consideration  deals  with  beef  only,  but  it  applies  with 
equal  force  to  all  meats  that  are  used  in  the  mess.  In  the  case  of 
defective  canned  goods,  of  which  there  have  been  large  quantities 
during  the  past  summer,  the  Quartermaster  General  has  provided 
that  all  cans  showing  "defective  vacuum"  shall  be  returned  for 
credit — that  is,  not  used  in  the  mess.  This  places  the  responsibility 
for  the  use  of  such  canned  goods  upon  the  mess  force  but  the  men 
must  be  taught  how  to  recognize  such  cans  and,  as  a  matter  of  fact, 
need  supervision  to  properly  protect  the  men  in  the  mess. 

The  mess  force  must  also  be  taught  how  to  recognize  and  elimi- 
nate, as  far  as  possible,  the  spoilage  of  vegetables.  They  must  be 
taught  the  best  methods  of  food  storage  for  different  types  of  foods ; 
the  temperatures  at  which  various  foods  may  best  be  kept ;  the  types 
of  containers  that  give  the  best  protection  for  food  with  the  reasons 
why  they  are  best. 

They  must  learn  how  to  handle  the  refrigerator.  This  is  an  ex- 
tremely important  point  since  certain  kinds  of  food  deteriorate 
rapidly  unless  kept  cold.  In  the  care  of  the  ice  box  they  must 
know  that  fresh  meat  will  keep  much  longer  at  a  given  tempera- 
ture if  its  surface  is  dry  than  if  it  is  wet;  that  the  ice-box  door 
must  never  be  opened  unless  necessary  and  then  closed  as  quickly 
as  possible;  they  must  learn  that  the  principle  underlying  refriger- 
ator consti-uction  is  to  allow  as  much  space  for  food  storage  and  as 
little  for  ice  as  possible  conducive  to  proper  refrigeration;  that, 
therefore,  the  space  for  ice  must  be  kept  filled  to  get  the  best  results, 
and  no  ice  used  from  the  ice  box  for  the  purpose  of  cooling  drinks; 
they  must  realize  that  the  refrigerator  cools  the  food  by  the  free 
circulation  of  air  over  the  ice  and  not  by  a  "  radiation  of  cold " 
from  the  ice — a  view  that  is  not  uncommon  among  men  of  the 
mess  forces;  that,  therefore,  the  meat  and  other  foods  must  not  be 
hung  in  the  box  in  such  a  way  as  to  restrict  the  movement  of  air, 
otherwise  it  will  take  the  box  longer  to  cool  off  after  it  has  been 
opened  or  warm  food  has  been  placed  inside.  These  and  a  number 
of  other  points  must  be  drilled  into  the  men  of  the  mess  force.  They 
must  be  followed  up,  however,  to  see  that  they  continue  to  use  the 


ATE  SEEVICE   MEDICAL.  421 

knowledge  they  have  received.  That  such  points  are  of  importance 
may  be  illustrated  by  the  experience  of  one  mess  in  which  meat  to 
the  value  of  $21  spoiled  within  three  days  during  the  month  of 
June.  Such  wastage  is  important  not  only  from  the  economic 
standpoint,  but  is  of  the  greatest  importance  from  that  of  the  mess 
where  it  occurred,  for  the  ration  allowance  is  fixed  and  if  food  is 
wasted  through  spoilage,  or  from  any  other, cause,  it  means  the  mess 
must  get  along  on  that  much  less  than  was  allowed  for  the  period. 

Again,  the  mess  force  must  be  taught  how  to  run  the  mess  with 
rigid  economy.  The  average  mess  will  be  found  to  waste  from  0.3 
to  0.8  pound  of  edible  food  per  man  per  day.  These  figures  look 
quite  harmless  perhaps  when  expressed  in  terms  of  the  waste  for 
each  man.  An  average  of  0.5  pound  per  man  per  day  means,  how- 
ever, a  daily  waste  of  600  pounds  in  a  camp  of  1,200  men  or  216,000 
pounds  per  year.  At  a  valuation  of  8  cents  per  pound,  a  low  average 
value,  this  represents  a  loss  of  $17,280.  At  this  same  rate  of 
wastage  an  Army  cantonment  of  40,000  men  would  waste  7,300,000 
pounds  per  year,  and  the  rate  if  maintained  throughout  the  Army 
would  be  equivalent  to  throwing  away  all  the  food  produced  by  a 
fair-sized  State.  More  than  this,  it  would  mean  that  great  ship 
space  would  have  to  be  used  for  foods  going  to  France  merely  to  be 
thrown  in  the  garbage  cans  of  the  over-seas  Army. 

It  has  been  shown  by  nutritional  survey  parties  in  the  field  that 
when  an  effort  is  made  to  keep  down  this  edible  waste  it  can  without 
diflficulty  be  reduced  to  0.07  to  0.15  pound  per  man  per  day.  This 
reduction  of  the  edible  waste  from  an  average  of  0.50  to  one  of  0.15 
pound  per  man  per  day  would  represent  an  annual  money  saving 
in  a  camp  of  1,200  men  of  $12,000,  and  this  low-  level  can  be  reached 
and  maintained  through  the  constant  supervision  of  the  nutrition 
officer.  He  can  make  a  frequent  determination  of  the  edible  waste 
in  the  various  post  messes  and  not  only  find  thereby  the  actual  waste 
but  the  waste  determination  will  serve  to  keep  the  necessity  for 
food  saving  ever  before  the  mess  force.  As  a  result  there  would  be 
not  only  less  waste  but  better  messes-  since  the  money  saved  could 
be  spent  for  delicacies,  fruits,  etc.,  that  go  far  in  making  the  mess 
more  satisfactory  to  the  men.  The  nutrition  officer  would  bring 
about  a  high  mess  efficiency  as  regards  saving,  by  teaching  the  cooks 
to  prepare  the  correct  quantity  of  food  so  as  to  avoid  as  much  as 
possible  the  production  of  left-overs;  by  teaching  them  how  to  use 
up  such  food  as  is  unavoidably  left  either  in  the  kitchen  or  on  the 
platters  and  vegetable  dishes  in  the  dining  room;  and  finally  by 
training  the  men  who  eat  in  the  mess  to  take  on  their  plates  no  more 
than  they  can  eat,  since  food  once  taken  on  the  private  plate  can 
not  be  used  again.  These  lines  of  training  can  be  successful  in  most 
cases  only  if  there  is  some  one  present  who  is  interested,  as  the  nutri- 


422  AIR  SERVICE   MEDICAL. 

tion  officer  would  be,  and  who  will  follow  up  the  instruction  and 
guard  against  a  return  of  the  mess  forces  to  former  careless  or  in- 
efficient methods. 

We  have  touched  upon  only  a  few  of  the  many  problems  for  the 
proper  solution  of  which  the  nutrition  officer  should  be  provided. 
These  will  suffice,  however,  to  show  that  there  is  a  very  real  need  in 
each  camp  for  a  man  who  is  trained  in  the  problems  of  food  and 
nutrition. 

Let  us  return  for  a  moment  to  the  special  needs  of  the  flier.  Fly- 
ing is  still  in  its  infancy  and  there  is  still  much  that  we  have  to 
learn  even  with  regard  to  the  proper  feeding  of  the  flier.  We  know, 
however,  that  he  must  be  fed  with  care ;  that  he  must  not  be  allowed 
to  eat  a  heavy  meal  immediately  before  undertaking  a  flight,  experi- 
ence having  shown  that  he  is  then  much  more  susceptible  to  gastric 
disturbance — nausea  and  vomiting — with  a  corresponding  rise  in  the 
element  of  danger.  It  seems  quite  evident  that  the  flier's  meals  must 
bear  a  certain  time  relationship  to  his  flying  hours.  If  he  stops  fly- 
ing at  noon  and  will  not  resume  flying  until  4  p.  m.,  it  is  proper  for 
him  to  eat  a  heavy  meal  at  noon.  It  will  not  do,  on  the  other  hand, 
for  him  to  rush  from  the  flying  field  to  the  mess  hall  for  a  heavy 
supper  and  then  back  to  the  flying  field  for  duty  immediately  after- 
wards. He  should  receive  only  light  food  in  small  quantity,  possibly 
a  sandwich,  at  such  times  and  take  the  full  meal,  if  he  requires  it, 
after  flying  for  the  day  has  stopped. 

Such  problems  as  these  can  not  be  handled  by  the  issuance  of  a 
general  order  for  all  the  fliers  in  the  different  camps.  It  is  no  more 
possible  to  handle  them  by  general  order  than  it  would  be  to  accom- 
plish the  work  of  the  flight  surgeon  or  physical  director  in  that  way. 
They  must  be  dealt  with  by  placing  an  experienced  man  at  the  post 
where  he  can  adapt  the  conditions  in  the  messes  to  the  changing 
conditions  in  the  camp  and  to  the  varying  needs  of  the  men  them- 
selves. Only  in  this  way  will  there  be  adequate  supervision.  Only 
in  this  way,  too,  may  we  extend  our  knowledge  with  regard  to  the 
care  of  the  flier  in  relation  to  his  food. 


CHAPTEE  XI. 
A  MESSAGE  TO  THE  FLIER. 


1.— VALUE  OF  OXYGEN  TO  THE  AVIATOR. 

To  you — for  you.  Aviator — this  message  comes.  It  brings  to  your 
attention  a  matter  of  vital  import;  it  carries  with  it  an  earnest  plea 
that  you  read  with  plastic  mind.  It  is  a  direct  appeal  for  your 
cooperation  in  maintaining  the  efficiency  of  our  Air  Force.  It  relates 
to  the  value  of  oxygen  in  altitude  flying.  We,  the  Medical  Officers 
attached  to  your  branch  of  the  Service,  have  devoted  ourselves  to 
one  object — to  take  care  of  you;  and  with  this  in  view,  we  marshal 
in  logical  array,  the  following  facts  for  your  benefit  : 

Oxygen  shortage  is  one  of  the  serious  problems  which  confronts 
the  aviator,  who,  owing  to  the  use  of  anti-aircraft  guns  in  present 
warfare,  must  do  much  flying  at  altitudes  ranging  from  16,000  to 
20,000  feet. 

The  human  organism  is  arranged  to  live  in  a  normal  atmosphere 
which  contains,  near  the  surface  of  the  earth,  about  21  per  cent  of 
oxygen  and  79  per  cent  of  nitrogen.  The  oxygen  is  that  element 
which  gives  and  maintains  life. 

As  man  ascends  in  the  air  he  leaves  his  natural  environment. 
The  density  of  the  atmosphere  becomes  successively  less  and  less ;  each 
cubic  foot  of  air  is  made  up  of  the  same  proportions  of  nitrogen 
and  oxj^gen,  but  the  total  quantity  of  each  is  successively  less  and 
less  as  higher  and  higher  altitude  is  attained.  Thus  at  an  elevation 
of  19,000  feet  the  density  of  the  air  has  diminished  to  the  extent 
that  each  cubic  foot  contains  only  one-half  the  amount  of  oxygen 
or  of  nitrogen  contained  in  a  cubic  foot  of  air  at  sea  level.  Man's 
bodily  requirements  of  oxygen  remain  the  same  as  at  sea  level; 
hence,  each  normal  intake  of  breath  at  this  altitude  furnishes  him 
with  just  one-half  the  oxygen  contained  in  each  intake  of  breath 
at  sea  level.  Going  to  still  higher  altitudes,  such  as  25,000  to  30,000 
feet,  this  discrepancy  in  oxygen,  with  its  noxious  effect,  becomes 
still  more  pronounced. 

The  human  organism  can,  however,  by  compensatory  arrange- 
ments, adapt  itself,  within  reasonable  limits,  to  a  decreased  oxygen 
percentage.  This  compensatory  quality  varies  in  the  individual,  for 
it  has  been  demonstrated  that  not  every  flier  is  qualified  to  work  in 

;423 


424  AIE  SERVICE   MEDICAL. 

a  high  altitude,  marked  differences  in  ability  to  withstand  it-s  effects 
revealing  themselves. 

In  a  man  with  normal  air  passages,  the  breathing  is  through  the 
nose  with  mouth  closed.  Very  few  air  men  are  able  to  continue  the 
nose  breathing  at  an  altitude  beyond  10,000  or  12,000  feet.  They 
have  a  sense  of  "lack  of  air"  and  open  the  mouth  in  breathing  to 
get  more  air.  The  breathing  becomes  quicker  and  deeper,  the  heart 
beats  faster  and  faster.  These  are  compensatory  changes.  They 
enable  the  individual  to  obtain  the  requisite  amount  of  oxygen  by 
increasing  the  volume  of  air  breathed  in  a  given  time  and  by  ex- 
posing a  greater  amount  of  blood  to  the  oxygen  in  the  air  cells  of 
the  lungs  in  a  given  moment. 

These  compensatory  agencies  enable  the  organism,  without  the 
individual  feeling  any  marked  inconvenience,  to  adapt  itself  to  fly 
at  altitudes  of  20,000  to  22,000  feet,  perhaps  even  higher,  for  a  short 
period.  Before  the  flier's  compensation  gives  out  he  will  feel  dizzy, 
but  is  perfectly  happy,  though  he  has  lost  his  judgment,  and  passes 
into  a  pleasant  condition  of  semi,  or  sometimes  total  unconsciousness. 

If  one  asks  a  number  of  pilots  who  have  been  regularly  flying  at 
15,000, 18,000,  or  even  20,000  feet  how  they  are  feeling,  the  usual  reply 
will  be  "  fine,"  "  perfectly  all  right,"  "  no  unpleasant  effect."  Though 
this  is  their  personal  impression,  we  know  that  they  are  all  affected  on 
flights  at  these  heights,  more  particularly  if  they  remain  long  at  high 
altitudes  or  fly  repeatedly  day  after  day.  A  person  at  an  altitude  of 
15,000  or  20,000  or  22,000  feet  may  feel  perfectly  fit  and  well,  but  he 
is  in  no  way  as  efficient  as  when  he  is  near  the  ground.  All  his  re- 
actions become  slower;  that  is  to  say,  he  uses  longer  time  to  judge 
distance,  to  aim  his  gun,  to  fire,  to  control  his  ship,  to  maneuver,  etc., 
although  he  is  not  conscious  of  this  impairment. 

When  the  compensatory  machinery  gives  out  partly  or  entirely  a 
series  of  symptoms  like  danger  signals  indicate  approaching  ineffi- 
ciency. 

The  most  pronounced  symptoms  of  oxygen  shortage  are  in  connec- 
tion with  the  central  nervous  system  and  generally  occur  after  flights 
at  an  altitude  of  over  15,000  or  16,000  feet.  Perhaps  the  most  fre- 
quently noted  symptom  is  headache,  accompanied  sometimes  by 
nausea.  This  may  last  some  hours  after  the  want  of  oxygen  has  been 
removed. 

Excessive  fatigue,  a  complete  collapse  of  energy,  far  beyond  the 
natural  weariness  induced  by  flying,  also  reveals  oxygen  starvation. 

Another  common  evidence  of  "thin  air"  is  vertigo,  a  symptom 
fraught  with  potential  calamity.  Disaster  lurks  at  its  heels,  for  the 
man  with  swaying  senses  is  no  longer  the  captain  of  his  ship. 

The  flier  who  is  suffering  from  want  of  oxygen  is  far  from  normal. 
He  may  be  exhilarated,  he  may  be  simply  dull  and  sleepy,  or,  if  he  is 


SHOWING  MASK  IN  POSITION. 
Floxiblo  tuliin;;  iiltached  to  mask  and  held  on  helmet  by  rublxT  liusiiing  in  flip. 
4251>-1 


1.  Flexible  metal  tubing  with  ruljber  end  connections  and  ruljljer  bnshins.  Pilot,  3'  0";  observer, 
5'0".  Bushing  tits  in  clip,  Fig.  No.  5.  2.  Rubber  mask.  3.  Dumm.v  transmitter  (made  of  wood). 
4.  Strap  clip;  to  be  sewed  on  helmet,  o.  Strap  clip  and  hose  clip;  to  be  sewed  on  helmet.  6.  Hose 
attachment  on  mask.  7.  Metal  buttons  for  holding  apron  to  mask.  8.  Box  of  12  Winton  disks. 
9.  *  Leather  apron  complete  with  straps,  corrugated  strips,  elastic,  and  buckle.  All  packed  in  one 
carton. 

*  To  reduce  wind  resistance,  apron  has  been  cut  off  on  dotted  lines. 


425b-2 


CAKTOX  CUXTAINIXG  MASK  COMPLETE  AND  FLEXIBLE  TUBING. 
425b-3 


MSii— Mt^iMMlffc*. 


425b-4 


425b-5 


i 


AIR  SERVICE   MEDICAL.  425 

in  a  position  of  danger,  he  may  fail  to  take  the  measures  necessary  for 
the  safety  of  himself  and  those  with  him,  even  when  he  is  well  aware 
of  the  danger.  This  extraordinai-y  impairment  of  judgment  is  ex- 
tremely characteristic,  the  person  himself  being  totally  imaware  of  it 
and  quite  confident  that  his  mind  is  absolutely  clear. 

Often,  too,  the  perception  is  affected.  One  sees  things  without 
being  able  to  understand  them  properly.  It  is  hard  to  read  an  instru- 
ment, and  positions  of  objects  are  misjudged.  Pain  itself  loses  some 
of  its  poignancy. 

These  symptoms,  some  trivial,  some  marked,  are  the  signposts  to 
Flying  Fatigue  within  whose  habitat  one  loses  the  energy,  the  will, 
and  the  ability  to  fly. 

A  strildng  instance  of  this  was  noted  during  an  inspection  by  one 
of  our  officers  of  a  certain  hospital  in  France.  One  ward  was  devoted 
to  the  care  of  fliers  suffering  from  "  oxygen  want."  During  the  week 
in  which  he  was  present  there  were  observed  22  such  cases.  The  en- 
tire group  of  men  from  all  appearances  looked  perfectly  healthy. 
Here  was  a  ward  full  of  young,  active  men  with  no  apparent  illness, 
not  a  single  man  was  injured  in  body  or  limb,  and  according  to  usual 
medical  standards  and  usual  methods  of  examination  each  one  of 
these  men  would  be  considered  perfectly  fit  for  service.  As  a  mat- 
•:er  of  fact  not  a  single  man  was  fit  for  service.  They  were  unable 
to  fly.  Their  chief  complaints  on  attempting  to  fly  were  headache, 
vertigo,  and  "lack  of  confidence."  There  were  two  causes — mental 
strain  from  long-continued  service  and  the  cumulative  effect  on  the 
nervous  system  of  an  insufficient  supply  of  oxygen. 

This  is  but  an  illustration  of  conditions  which  obtain  wherever  men 
are  flying.  All  these  symptoms  are  effects  of  a  decrease  in  the  oxygen 
contained  in  the  air  at  high  altitudes,  and  can  be  absolutely  and  en- 
tirely obviated  by  the  proper  administration  of  oxygen  to  the  airman. 
It  should  at  once  be  realized  that  the  aviator  supplied  with  oxygen 
while  flying  is  very  much  more  efficient  than  the  same  man  flying  with- 
out oxygen,  and  becomes  therefore,  of  so  much  more  value  as  a  fight- 
ing force.  Take,  for  example,  two  pilots  of  equal  ability,  flying 
machines  being  identical  in  every  respect,  that  man  supplied  with  oxy- 
gen will  always  bring  down  the  other  machine  because  he  has  retained 
all  his  judgment  and  rapidity  of  decision  and  movement  unimpaired. 
He  will  be  able  to  outmaneuver  and  outwit  his  opponent  and  fire  his 
gun  before  the  other  has  even  made  up  his  mind  what  to  do.  Not 
only  that,  when  he  returns  to  the  ground  after  prolonged  flight  he 
will  be  fresh  and  able  to  start  out  on  a  new  trip,  while  the  man  flying 
without  oxygen  will  be  tired  out  and  unable  to  do  any  more  work  that 
day  and  possibly  the  next.  The  administrafon  of  oxygen  must  of 
course  in  no  way  impair  the  comfort  of  the  movements  of  the  airman, 
nor  should  he  have  anything  further  to  do  while  flying,  as  he  already 


426 


AIK   SERVICE   MEDICAL. 


has  plenty  to  look  after,  in  his  machine.  For  this  reason  the  apparatus 
used  must  be  simple,  safe,  and  entirely  automatic;  automatic  in  the 
sense  that  while  the  machine  stands  on  the  ground  no  oxygen  is  given 
off,  but  when  it  rises  in  the  air  the  increasing  deficiency  in  the  oxygen 
content  of  the  air  is  automatically  made  up  for  by  the  delivery  of  oxy- 


"  Fainting  in  tlie  air."    A  potential  calamity  if  the  flier  is  not  physically  fit. 

gen  by  the  apparatus,  without  any   personal  attention   from  the 
airman. 

Our  Government  has  placed  at  your  disposal  an  apparatus  which 
meets  these  tests.  It  is  adapted  for  all  planes  flying  to  high  altitudes. 
It  is  the  Dreyer  apparatus  designed  by  Col.  Georges  Dreyer  for  the 
Royal  Air  Force  and  adapted  by  our  service.  This  apparatus  con- 
sists of: 


AIR  SERVICE   MEDICAL. 


427 


First,  of  a  steel  tank  or  tanks  in  which  oxygen  is  stored  under  high 
pressure,  e.  g.,  150  atmospheres;  in  other  words,  500  liters  of  oxygen 
\P  put  in  a  small  steel  bottle  of  a  capacity  of  only  3.3  liters. 


\\,N 


V 

\ 


\ 


■\\ 


\x  '""mm:;: 

mwmiMJi  ■'\. 


'l/i;mill!n 


,^^yy^^-A.. 


'  Wings' dropping  off  plane."     All  parts  of  the.  plane  must  be  well  constructed  if  disaster 

Is  to  be  averted. 

Second,  of  the  automatic  oxygen  apparatus  where  the  pressure  of 
the  oxygen  is  reduced  from  a  high  to  a  low  pressure  through  a  special 
reducing  valve  and  then  delivered  in  increasing  quantities  as  you  rise 
in  the  air  by  means  of  an  aneroid-controlled  valve,  while  no  delivery 


428  AIR   SERVIOE  MEDICAL. 

takes  place  on  the  ground  level.  The  apparatus  is  regulated  in  such 
a  manner  that  the  deficiency  of  oxygen  in  the  air  at  any  altitude  is 
always  just  compensated  for  by  the  oxygen  delivered  by  the  appa- 
ratus. To  visualize  to  the  airman  that  the  apparatus  is  functioning, 
it  is  provided  with  a  flow  indicator,  which,  starting  at  about  6,000 
feet,  will  revolve  faster  and  faster  as  the  machine  rises  in  the  air, 
owing  to  the  greater  and  greater  amounts  of  oxygen  passing  through 
the  apparatus.  As  long  as  the  indicator  rotates  quickly  the  apparatus 
is  functioning  properly. 

Third,  of  an  india-rubber  mask  worn  over  the  mouth  and  nose ;  in 
this  mask  is  also  embodied  a  microphone  for  wireless  communication. 
The  mask  is  connected  with  the  apparatus  by  means  of  a  light  flexible 
metallic  tube.  The  functioning  of  the  apparatus  is  perfectly  inde- 
pendent of  any  drop  of  temperature  that  may  take  place  in  the  air 
as  well  as  whether  it  is  working  from  a  full  tank,  e.  g.,  150  atmos- 
pheres pressure  or  a  practically  empty  tank,  e.  g.,  a  few  atmospheres 
pressure. 

The  wearing  of  the  mask  does  not  interfere  with  the  pilot's  effi- 
ciency in  managing  the  plane.  It  has  been  tried  out  by  many 
officers,  all  of  whom  stated  that  the  slight  discomfort  on  first  putting 
it  on  quickly  wore  oil  and  that  when  in  the  air  this  discomfort  was 
entirely  unnoticed.  This  mask  has  combined  with  it  an  interphone, 
whereby  pilot  and  observer  can  continuously  talk  with  ease  while  in 
the  air.  This  advantage  was  a  source  of  delight  to  all  who  have  used 
the  set.  This  mask  and  phone  set  have  been  officially  adopted  by  the 
service  and  will  be  ultimately  a  part  of  the  equipment  of  all  planes. 

Experience  proves  that  once  the  flier  has  realized  the  benefits  de- 
rived he  usually  refuses  or  hates  the  idea  of  flying  without  oxygen. 

We  have  given  you  a  simple  description  of  the  Dreyer  apparatus. 
In  this  connection  interview's  with  the  Commanding  Officers,  Fliers, 
and  Observers  at  the  British  Front  illustrate  its  value.  One  message 
from  the  British  Front  tells  the  story  in  a  sentence : 

The Squadron,  which,  as  you  know,  has  been  using  the  oxygen  appa- 
ratus for  months,  is  doing  six  times  the  amount  of  work  that  any  other  squadron 
is  doing  without  oxygen. 

Maj.  D ,  commanding  officer, Squadron,  Eoyal  Flying 

Corps : 

We  advise  our  men  to  fix  the  mask  in  position  before  leaving  the  ground. 
When  using  the  Dreyer  apparatus  at  an  altitude  of  over  10,000  feet  it  is  best 
for  the  pilot  to  adjust  the  mask  and  wear  it  from  the  time  he  starts  until  the 
time  he  comes  back  and  gets  out  of  the  plane.  There  is  no  question  that  these 
men  in  my  command  who  have  used  the  oxygen  apparatus  are  not  by  any  means 
as  tired  as  they  used  to  be  before  they  used  this  apparatus.  Since  the  use  of 
the  oxygen  the  men  have  not  complained  of  any  headaches,  fatigue  (except 
what  you  might  call  ordinary  fatigue),  or  vertigo. 


AIR  SERVICE   MEDICAL.  429 

Maj.  D ,  commands  the  squadron  of  high  fliers  exclusively, 

and  they  have  been  using  the  Dreyer  oxygen  apparatus  for  two  years. 

Capt.  P ,  pilot,  who  has  been  flying  at  an  average  height  of 

20,000  feet: 

Befoi'e  the  oxygen  apparatus  was  used  I  used  to  suffer  a  great  deal  from  flying 
at  high  altitudes.  I  would  notice  a  palpitation  of  my  heart  not  only  in  the 
air  at  this  high  altitude  but  also  on  the  ground  at  a  period  of  24  hours  after 
flight.  I  would  have  a  bad  headache  not  only  in  the  air  but  also  after  coming 
down.  This  would  last  from  five  to  six  hours.  I  used  to  get  this  palpitation  of 
the  heart  and  headache  when  I  would  fly  over  16,000  feet;  I  would  also  feel 
"  rotten  and  done  up,"  and  as  time  went  on  it  would  become  so  bad  I  was  so 
tired  I  could  not  sleep  Monday  afternoon,  Monday  night,  or  all  Tuesday,  and  I 
would  have  my  first  sleep  on  Tuesday  night.  I  do  not  know  how  to  explain 
why  I  could  not  sleep ;  it  was  apparently  not  in  any  way  due  to  "  nervousness." 

Since  I  have  used  the  ox:ygen  apparatus  I  have  had  no  palpitation,  no  head- 
ache, no  fatigue  at  all,  and  I  sleep  normally. 

An  observer: 

This  man  says  that  after  flying  at  an  average  height  of  20,000  feet  several 
weelJS,  also  very  active  in  the  use  of  the  machine  gun,  he  did  not  in  any  way 
feel  the  need  of  oxygen.  But  after  seeing  active  service  for  six  months  he 
states  he  has  "  vertigo  and  fatigue,"  and  after  he  has  come  down  from  a  great 
height  he  now  feels  "  done  up." 

Isolated  cases  these,  but  the  British  squadron  commanders,  who 
have  felt  the  comfort  and  benefit  accruing  from  the  oxygen  apparatus 
have  made  its  use  compulsory  with  their  squadrons. 

It  is  this  apparatus  which  has  been  adopted  by  the  Air  Service, 
United  States  Army.  Men,  this  is  a  gift  horse,  pure  and  simple. 
Don't  stand  on  the  order  of  the  shape  of  its  mouth,  but  regard  it  rather 
as  a  trusty  friend  that  will  carry  you  safely  at  trying  altitudes,  pull 
you  out  of  many  a  rough  rut  of  flagging  force,  and  bring  you  back 
to  terra  firma  with  the  least  expenditure  of  your  physical  strength 
and  nervous  energy.  This  is  the  mission  of  the  Dreyer  apparatus,  one 
of  far-reaching  importance.  It  produces  energy,  sustains  life,  and 
tends  to  keep  you  a  live  wire  in  our  air  force. 

Can  you  afford  to  be  less  alert  than  your  enemy  ?  Can  you  refuse 
to  use  any  weapon  placed  at  your  disposal?  Have  you  not  need  of 
all  your  strength  when  your  great  moment  comes?  Then  be  fit;  keep 
fit !     Use  your  oxygen  apparatus. 

2.— DESCRIPTION,    INSTALLATION,    AND    GENERAL    OPERATING 
INSTRUCTIONS  FOR  AERO  OXYGEN  APPARATUS. 

The  oxygen  equipment  used  to  furnish  oxygen  to  the  personnel 
of  the  planes  consists  of  the  following  apparatus  and  parts : 

Oxygen  apparatus. 
Low-pressure  Y  connection. 
Low-pressure  connection  tubing. 


430  AIR   SEBVICE    MEDICAL. 

Low-pressure  L  connections. 

Masks. 

High-pressure  tubing  and  its  connections. 

Manifold  connections. 

Tanks  and  valves. 

Permanent  oxygen  crates. 

All  of  this  equipment  is  installed  on  the  plane  with  exception  of 
crates.  There  is  considerable  operating  and  maintenance  equipment 
which  is  not  used  on  the  plane,  such  as  pumps,  refilling  stations, 
large  tanks,  etc.,  which  are  necessary  to  maintain  a  constant  supply 
of  clean  oxygen. 

The  functioning  of  the  oxygen  equipment  is  to  furnish  the  proper 
quantity  of  oxygen  to  fliers  at  all  times  and  altitudes  for  the  proper 
sustenance  for  maximum  human  efficiency.  The  oxygen  is  stored  in 
the  small  tanks  under  a  pressure  of  2,250  pounds  per  square  inch. 
This  pressure  is  automatically  reduced  and  the  required  amount  auto- 
matically delivered  by  the  apparatus. 

All  equipment  has  been  carefully  designed  for  complete  standardi- 
zation, continuity  of  operation,  reliability,  and  maximum  efficiency. 
The  entire  equipment  is  automatic.  There  are  no  exposed  moving 
parts  or  elements.  All  the  flier  has  to  do  is  to  turn  on  the  oxygen 
at  the  tank  and  put  on  his  oxygen  mask.  The  apparatus  automati- 
,  cally  accomplishes  the  results. 

The  apparatus  now  in  production  is  known  as  the  Dreyer  type. 
It  was  adopted  by  our  Air  Service  December  5,  1917.  It  is  approxi- 
mately 6  by  5  by  2  inches  high  and  weighs  about  4  pounds.  All  work- 
ing parts  are  contained  in  a  pressed  steel  case  having  the  necessary 
openings  for  connections,  gauges,  etc.  It  consists  of  four  elementary 
parts — the  reducing  valve,  the  control  valve,  aneroid  valve,  and  flow 
indicator.  Mounted  on  the  reducing  valve  is  a  higher-pressure 
gauge,  which  shows  the  tank  pressure  and  quantity  of  oxygen  in 
the  tanks.  The  scale  of  this  gauge  is  so  arranged  that  when  the 
oxygen  is  getting  low  the  quantity  will  indicate  §o  by  appearing  in 
a  marked  danger  zone.  The  reducing  valve  is  a  delicate  but  simple 
device  which  automatically  reduces  the  tank  pressure  from  an  aver- 
age of  50  pounds  to  2,250  pounds  to  a  final  pressure  of  about  3  pounds 
gauge.  This  is  accomplished  automatically,  and  no  adjustments  are 
necessary. 

From  the  reducing  valve  the  low-pressure  oxygen  is  delivered  t(> 
the  control  valve.  This  is  a  simple  arrangement  which  controls  the 
flow  of  oxygen  for  either  one  or  two  men.  The  handle  of  this  valve 
extends  through  the  case,  is  plainly  marked,  and  easily  handled. 
Before  flying  this  valve  is  set  so  that  the  apparatus  will  deliver  oxy- 
gen for  the  required  number  of  persons. 


AIR  SERVICE   MEDICAL.  431 

From  the  control  valve  the  oxygen  is  delivered  to  the  aneroid 
valve,  which  consists  of  a  high-grade  cylinder  and  piston,  with  the 
necessary  grooves  and  openings,  which  are  actuated  by  set  of  aner- 
oids. This  valve  controls  the  required  quantity,  delivering  oxygen 
for  all  altitudes  up  to  and  including  30,000  feet  and  for  either  one 
or  two  men. 

From  the  aneroid  valve  the  oxygen  is  delivered  to  the  flow  indi- 
cator, which  is  a  simple  device  indicating  that  oxygen  is  flowing. 
From  the  indicator  the  oxygen  is  delivered  to  the  low-pressure 
connection. 

The  low-pressure  Y  connection  is  a  simple  fitting,  one  side  of 
which  is  fitted  with  a  cock  so  that  oxygen  can  be  delivered  to  either 
one  or  two  men. 

Low  pressure  comuctiQn  tubing. — Each  plane  is  installed  with 
low-pressure  connection  tubing,  which  conveys  the  oxygen  from  the 
Y  connection  to  the  L  connection  for  both  pilot  and  observer. 

Low  pressure  L  connections  are  simple  L  fittings — one  located  in 
the  observer's  cockpit  and  one  in  the  pilot's  cockpit — ^to  which  is 
attached  the  mask  connection. 

Masks. — The  present  type  of  mask  in  production  consists  of  a 
rubber  piece  which  covers  both  the  nose  and  mouth,  into  which  is 
fitted  the  radio  transmitter.  Wlien  radio  is  not  used  this  transmitter 
is  replaced  by  a  wooden  block.  The  rubber  mask  is  contained  in  a 
leather  apron.  The  entire  mask  is  attached  to  the  face  by  means  of 
straps  from  the  helmet  to  the  leather  apron.  Each  mask  is  shipped 
complete  with  the  proper  length  of  low-pressure  tubing  for  both 
pilot  and  observer.  Necessary  attaching  clasps  which  can  be  used 
are  riveted  to  helmet. 

There  is  another  type  of  mask  which  is  at  the  present  time  being 
considered,  which  consists  of  a  rubber  piece  that  covers  the  nose  only 
and  is  in  no  way  combined  with  the  radio.  This  leaves  the  mouth 
free  for  articulation.  This  type  of  mask  offers  no  wind  resistance 
whatever  and  is  very  light  and  comfortable. 

High-pressure  tubing  consists  of  the  necessary  length  of  high- 
pressure  copper  tubing,  to  which  is  attached  the  proper  end  connec- 
tions for  connecting  to  the  apparatus  and  the  tanks  or  manifold 
connections. 

Manifold  connection  is  a  flexible  T  connection  and  is  used  to  connect 
two  tanks  in  parallel. 

Tanks  and  valves. — The  standard  zero  tank  designed  to  serve  one 
man  has  volumetric  capacity  of  approximately  210  cubic  inches  and 
contains  500  liters  of  atmospheric  oxygen  under  a  final  pressure  of 
2,250  pounds.  This  capacity  is  figured  to  supply  one  man  with  plenty 
of  oxygen  at  all  altitudes  for  from  one  to  three  hours. 


432  AIB  SEEVICE   MEDICAL. 

Two  tanks  are  used  for  a  two-man  plane;  they  are  connected  in 
parallel  by  means  of  the  manifold  connections ;  each  tank  is  furnished 
with  an  extremely  light  but  very  strong  and  rugged  valve. 

The  first  tanks  furnished  weighed  approximately  12  pounds  each. 
The  later  tanks  will  weigh  only  7  pounds  each.  All  tanks  will  have 
approximately  the  same  external  dimensions ;  that  is,  about  19  to  20 
inches  long  by  about  3^  to  3|  inches  in  diameter. 

Permanent  oxygen  crates  consist  of  a  rugged  case,  which  will  con- 
tain five  small  tanks,  tanks  being  securely  held  so  that  valves  will  not 
be  damaged.  All  crates  have  no  external  obstructions;  can  be  easily 
piled  upon  a  truck  or  carried  in  a  cycle  car.  These  crates  have  been 
designed  for  permanently  conveying  oxygen  tanks  from  point  to  point 
overseas. 

Each  DH-4  plane  is  equipped  with  low-pressure  tubing,  L  connec- 
tions, holes  for  mounting  the  oxygen  apparatus,  and  brackets  for  con- 
taining the  tanks.  The  balance  of  the  oxygen  equipment  is  shipped 
directly  overseas  to  the  Aviation  General  Supply  Depot.  With  each 
apparatus  is  shipped  the  high-pressure  connection,  Y  connection,  and 
the  necessary  screws  for  attaching  the  apparatus  to  the  plane. 

All  masks  are  shipped  directly  overseas  complete.  All  manifold 
connections  are  shipped  separately  overseas.  Tanks  and  valves  are 
shipped  overseas  in  permanent  oxygen  crates. 

All  tubing,  both  high  and  low  pressure,  before  shipment,  is  cleaned. 
It  is  vitally  necessary  that  each  fitting  be  thoroughly  cleaned  before 
assembly  in  order  to  eliminate  dirt. 

3.— STATEMENT  BY  AN  OFFICER  OF  A  TESTING  SQUADRON  RE- 
GARDING ALTITUDE  RECORD  WHICH  WAS  ESTABLISHED 
SEPTEMBER  18,  1918.* 

"  In  order  to  take  an  aeroplane  to  a  higher  altitude  than  any  other 
pilot  in  the  world,  I  found  that  it  would  require  more  than  one  or 
two  attempts.  I  made  three  attempts.  The  first  one  took  me  to 
24,000  feet,  the  second  to  27,000  feet,  and  the  last  one  to  28,900  feet, 
but  now  I  feel  certain  that  I  can  get  to  at  least  30,000  feet. 

"  The  cold  thin  air  is  one's  greatest  adversary.  First  of  all,  one 
must  make  a  study  of  the  performance  of  his  motor  at  those  high  alti- 
tudes. This  I  did,  and  made  the  necessary  changes  before  trying  again. 
Loss  of  power,  due  to  rich  carburation,  thin  air,  and  the  cooling  of 
the  motor,  are  the  main  things  to  overcome.  Eich  carburation  can 
be  partially  overcome  by  increasing  the  volume  of  air  going  through 
the  carburetor,  either  by  a  mechanical  process,  air  bottles,  or  other 
induced  pressure  systems.  I  believe,  however,  that  high-compression 
pistons  can  be  fitted  very  satisfactorily.  This,  of  course,  necessitates 
a  throttled  motor  at  low  altitudes.  An  aneroid  adjustment  could  be 
fitted  to  prevent  the  throttle  from  being  opened  wide  at  low  altitudes. 


♦  Record  made  by  Capt.  R.  W.  Schroeder. 


AIR  SERVICE   MEDICAL.  433 

"  I  used  a  set  of  high-compression  pistons  and  paid  keen  attention 
to  my  throttle,  which,  however,  I  was  unable  to  open  wide,  even  at  my 
highest  altitude,  for  I  noticed  that  when  I  did  the  motor  lost  R.  P.  M. 
This  was  due,  I  think,  to  rich  carburation.  I  maintained  my  R.  P.  M. 
partially  by  feeding  oxygen  into  my  carburetor.  A  very  efficient  set 
of  radiator  shutters  are  needed  to  maintain  the  proper  motor  heat, 
these  I  did  not  have.  A  very  positive  oxygen  regulator  and  face 
mask  should  be  used.  These  were  unobtainable,  for  the  sets  I  had 
previously  tried  out  had  failed  to  function  above  21,000  feet.  Fur- 
thermore, the  face  mask  pressed  so  tight  to  my  face  that  it  interfered 
with  the  flow  of  blood  and  my  face  grew  numb.  So  I  used  a  rubber 
hose  direct  from  the  oxygen  bottle,  which  I  regulated  with  a  valve 
on  the  bottle.  The  hose  was  placed  in  my  mouth  so  that  I  could 
breathe  air  and  oxygen  at  the  same  time.  I  also  pressed  my  tongue 
against  the  end  of  the  hose  in  order  to  tell  if  the  oxj-gen  was  still 
flowing.  This  method  worked  very  satisfactorily,  except  that  the 
oxygen  bottle  and  the  rubber  tube  gathered  about  a  quarter  of  an 
inch  of  frost,  which  made  it  very  unpleasant. 

"  The  following  experiences  and  sensations  I  noticed  during  my 
flight  were  due  mostly  to  lack  of  oxygen : 

"  I  took  off  at  1.45  p.  m.  Wednesda3\  September  18,  1918,  and 
made  a  steadj^  circular  climb,  passing  through  clouds  at  8,000  feet, 
12,000  feet,  and  16,000  feet.  At  20,000  feet,  while  still  climbing  in 
large  circles,  my  goggles  became  frosted,  making  it  very  difficult 
for  me  to  watch  my  instruments.  When  I  reached  25,000  feet  I 
noticed  the  sun  growing  very  dim,  I  could  hardly  hear  my  motor  run, 
and  I  felt  very  hungry.  The  trend  of  my  thoughts  was  that  it 
must  be  getting  late,  that  evening  must  be  coming  on ;  but  I  was  still 
climbing,  so  thought  I  might  as  well  stick  to  it  a  little  longer,  for 
I  knew  I  could  reach  my  ceiling  pretty  soon,  then  I  should  go 
down,  and  even  though  it  were  dark  I  could  land  all  right,  for  I 
had  made  night  landings -many  times  before,  and  so  I  went  on  talk- 
ing to  myself,  and  this  I  felt  was  a  good  sign  to  begin  taking  oxygen, 
and  I  did.  I  was  then  over  25,000  feet,  and  as  soon  as  I  started  to  in- 
hale the  oxygen  the  sun  grew  bright  again,  my  motor  began  to  ex- 
haust so  loud  that  it  seemed  something  must  be  wrong  with  it.  I 
was  no  longer  hungry  and  the  day  seemed  to  be  a  most  beautiful  one. 
I  felt  like  singing  with  sheer  joy  as  I  gazed  about  through  a  small 
portion  of  my  goggles  which  had  no  frost,  due  to  a  drop  of  oil  which 
had  splashed  on  them  from  the  motor. 

"  It  was  wonderful  to  see  the  very  clear  blue  sky  with  the  clouds 
thousands  of  feet  below.  The  frost  on  mj-  goggles  bothered  me  veiy 
much.  At  times  I  had  to  remove  my  glove  in  order  to  put  the  warm 
palm  of  my  hand  on  the  glass  to  thaw  the  frost.  I  did  this  about 
every  10  minutes,  so  that  I  could  take  the  proper  readings  of  the 


434  AIE  SEEVICE   MEDICAL. 

instruments,  which  I  marked  down  on  my  data  pad.  I  believe  that 
if  my  goggles  had  been  better  ventilated  they  would  not  have 
frosted.  When  I  was  about  27,000  feet  I  had  to  remove  my  gog- 
gles, as  I  was  unable  to  keep  a  steady  climb.  My  hands  by  this 
time  were  numb,  and  worried  me  considerably.  The  cold  raw  air 
made  my  eyes  water,  and  I  was  compelled  to  fly  with  my  head  well 
down  inside  the  cockpit. 

"  I  kept  at  it  until  my  oxygen  gave  out,  and  at  that  point  I  noticed 
my  aneroid  indicated  very  nearly  29,000.  The  thermometer  showed 
32°  below  zero  C.  and  the  R.  P.  M.  had  dropped  from  1,600  to 
1,560.  This  is  considered  very  good.  But  the  lack  of  oxygen  was 
affecting  me,  I  was  beginning  to  get  cross,  and  I  could  not  under- 
stand why  I  was  only  29,000  feet  after  climbing  for  so  long  a  time. 
I  remember  that  the  horizon  seemed  to  be  very  much  out  of  place, 
but  I  felt  that  I  was  flying  correctly  and  that  I  was  right  and  the 
horizon  was  wrong. 

"About  this  time  the  motor  quit.  I  was  out  of  gasoline,  so  I  de- 
scended in  a  large  spiral.  When  I  had  descended  to  about  20,000 
feet  I  began  to  feel  much  better  and  realized  that  the  lack  of  oxygen 
had  affected  me.  I  passed  down  through  the  clouds  at  16,000  feet, 
and  as  I  remember  it  was  snowing  from  these  clouds  upon  the  next 
layer  some  4,000  feet  below.  I  am  not  positive  of  this,  as  I  may  have 
been  affected  by  the  lack  of  oxygen.  I  noticed  as  I  descended  that  the 
air  seemed  to  be  very  thick  and  stufi'y,  but  very  nice  and  warm. 
I  did  not  see  the  ground  from  the  time  I  went  up  through  the  clouds 
above  Dayton,  Ohio,  until  I  came  down  through  them  again  at  4,000 
feet  above  Canton,  Ohio,  over  200  miles  from  where  I  started. 

"  I  was  lost  beyond  a  doubt,  with  a  dead  engine  over  very  rough 
country.  I  landed  O.  K.,  and  broke  the  tip  of  my  propeller,  which 
was  standing  vertical,  when  I  rolled  into  a  depression  in  the  ground. 
However,  I  did  not  nose  over  or  do  any  other  damage  to  the  plane 
or  myself.    I  flew  back  to  Dayton  with  a  new  propeller. 

"  My  lips  and  four  of  my  fingers  were  frozen  and  required  medical 
attention.  Electrically  heated  clothing  would  have  been  very  well 
used,  but  I  dressed  as  light  as  possible  to  avoid  the  extra  weight,  as 
I  had  stripped  the  entire  plane  of  all  unnecessary  load.  This  was 
done  to  assist  me  in  climbing. 

"Attached  are  photographs  of  the  performance  curves  and  the  bar- 
ograph curves,  also  a  report  of  the  corrections  to  show  true  altitude 
above  sea  level,  as  compiled  by  Lieut.  George  B.  Patterson,  officer  in 
charge  of  all  performance  reports  of  the  testing  squadron. 

"  If  this  record  can  be  made  official,  it  will  be  the  first  world's  avia- 
tion record  held  by  America  since  August,  1911.  At  that  time  the 
late  Lincoln  Beachey  made  a  climb  to  eleven  thousand  and  some  odd 
feet  at  Chicago,  111." 


INDEX. 


,»  Page. 

Absorbents,  solutions  used  as * 374,  375 

Accidents: 

Error  of  judgment  as  cause  of 267 

Physical  defects  cause  of  90  per  cent  of 207 

Acclimatization ,  value  of  factors  of 160-162 

Adenoids 235 

After-nystagmus  times,  with  successive  rotations,  decrease  of 316 

Air  analysis,  summary  for  the  procedure  for 372-373 

Air  Medical  Service: 

Organization  of 228 

Requirements  fixed  by  Chief  Surgeon  as  to  physical  condition  of  men  se- 
lected   228 

Requirements  of  the  individual  for  efficiency  of 293,  294,  295, 296 

Airplanes: 

Altitudes  attained  by 23 

Development  of,  among  the  allies,  a  story  of  sportsmanship 10 

Extraordinarj'^  development  due  to  necessity  arising  from  actual  warfare. .  10 

Failures  of,  responsible  for  limited  losses 30 

Interest  in,  by  European  nations,  when  first  invented 10 

Losses  of,  responsibilities  for 30 

Progress  in  development  of 7, 10 

Realization  of  the  possibilities  of  the  airplane  as  a  factor  in  battle 10 

Air  8er\dce,  policy  of  placing  worn-out  men  in 11,  29 

Air  superiority  held  by  Germans  during  early  stages  of  the  war 10 

Altitude: 

Changes,  adaptive 142 

Changes,  alveolar 155 

Effect  of ,  on  the  eye 270 

Effect  of,  on  man  and  animals 137 

High- 
Ability  to  withstand 162 

Blood  concentration  at 145 

Circulation  at 146 

Comparisons  of  ventilation  of  lungs  at,  and  at  sea  level 154 

Comparisons  of  athletic  and  nonathletic  individuals  in  withstanding.  163 

Effect  on  man  during  residence  on  Pike's  Peak ^ 146 

Fall  in  alveolar  dioxide  pressure 157 

Increased  ventilation  of  lungs  at 157 

Oxygen  pressure  of  arterial  blood  at 159-160 

Physical  fitness  to  withstand 162-163 

Proportion  of  fliers  capable  of  attaining 24 

Rebreathing  apparatus  for  attaining 25 

Respiration  at 153 

Sequence  in  blood  changes  at 144 

89118—19 29  435 


436  INDEX. 

Altitude — Continued.  Page 

Limits,  outline  of  conditions 296 

Physiology 137 

Relation  of,  pressure,  and  oxygen 166 

Respiratory  observations 158-159 

Sickness,  cause  of 167 

Alveolar  air: 

Altitude  changes 155 

Analysis  of,  during  rehreathing  test 176 

Partial  pressure  of  gases  in .' 155 

Percentage  of  gases  in 155 

Pressures,  experiments  made  to  show  changes  in 198 

Apparatus  for  acquiring  experience  and  training  without  leaving  the  ground ...        32 

Apparatus,  rehreathing,  care  of 369 

Arrhythmia 218 

Arterial  pressures 146, 148 

Greater  at  high  altitudes 152 

Arteriosclerosis 217 

Asphyxiation,  psychological  effects  of 295 

Association  reaction  times 329-330 

"Athletic"  hearts 226 

Athletics,  mass 395 

Auditory  tests 315-316 

Average  wedge,  per  cent  transmission  and  density  of 362 

Aviation  Examining  Board,  Washington,  D.  C 37 

Aviation  Service: 

Applications  for^ — 

At  Washington,  D.  C 89,  90,  91, 92,  93 

Percentage  disqualified 86,  87 

Rejections  of,  causes  for 85, 86 

Casualty  list,  reduction  of  methods  for 334-335 

Classification  of  personality  record 340, 341, 342 

Examination  of  applicants  for .' 37 

Examination  for,  at  Washington,  D.  C,  rejections,  causes  for 91 

Examinations  for,  acceptances  and  rejections  (table) 92, 93 

Examinations  for,  applicants  operated  on  for  acceptance 92,  93 

Examinations  for,  acceptances 89 

Examinations  for,  rejections 90 

Excessive  smoking  taboo 394,  395 

High  personal  standard  for 392 

Individual  fitness  for,  cases  cited 331,  332,  333,  334 

Overeating  detrimental  for 394 

Physical  director 391,  392,  393 

Problems  of,  psychological  investigations  of 3]  6 

Representatives  of,  responsible  for  determination  of  fitness  of  applicants  for .        37 

Right  living  the  basis  for 393 

Special  conditions  to  which  the  flier  may  be  subjected 295 

Unfitness  for,  classification  of  personality  rating 339 

A — Safe,  nervous,  and  mentally  stable 339 

B — Safe,  with  limitations 339 

C — Questionable ;  no  definite  conclusion  reached 340 

D — Needs  special  attention 340 

E— Unsafe , 340 


INDEX.  437 

Aviators:  Page. 

Advice  on  keeping  nerve 335-336 

Altitudes  capable  of  attainment  by 24 

Carelessness  in  selection  of,  in  early  stages  of  war 11 

Classification  of,  as  to  fitness  for  different  types  of  air  acti^'ities 14, 23 

Deterioration  of,  causes  of 296 

Flier  at  the  front  safer  than  infantiyman  in  trench 11 

Ix)W  oxygen,  effect  of,  upon  mental  processes. . .» 26 

Low  oxygen,  effect  of,  upon  vision 26 

Ninety  per  cent  of  losses  due  to  physical  defects 30 

Oxygen,  apparatus  for  supplying 25 

Oxygen,  value  of,  in  altitude  flying 423 

Physical  examinations  of  applicants  in  first  call 263-266 

Physical  fitness  of 13 

Physical  training  for 402 

Practical  requirements 298 

Proportion  of  fliers  capable  of  attaining  high  altitudes 24 

Psychological  qualifications  of •. 308-309 

Rating  tests 298,  299,  300 

Recuperative  furloughs  for,  recommended 400 

Reexamination  of,  plan  for 97 

Routine  monthly  examination  of  the  ej^e  of,  suggested 361 

Selection  of,  method  of 17,  97 

"  Staleness  "  of,  induced  by  excessive  heat 400 

Study  of,  as  an  individual 13 

Supervision  of 337 

Though  physically  fit,  not  necessarily  fitted  for  all  types  of  air  activities. .        23 

Balloon  ascension,  historic  experience  in,  by  Tissandier 140 

Barany  chair,  American  modification  of 42 

Barometric  pressure 151 

Birley,  Maj.  J.  L.,  articles  by,  relative  to  medical  service  attached  to  Royal 

Flying  Corps 105, 110, 121 

Blood  changes  at  high  altitude 143-144 

Blood  circulation : 

"Athletic"  hearts 226 

Arrhythmia 218 

Arteriosclerosis 217 

Changes  of,  causes  of 151 

Circulatory  collapse 213 

Effects  of  low  atmospheric  pressure  on 205-220 

Effect  of  low  oxygen  tension  on  circulatory  physiology 208 

Effects  on  pathological  cases 217 

Heart  strain 213-214 

Increasing  the  blood  flow 210 

Insufficient  compensation 212 

Oxygen  deficiency,  compensation  for 209 

Physiology  of 207 

Pike 's  Peak,  blood  cii'culation  observations  made  on 173 

Pulse  rate  as  indicator  of  oxygen  want , 173 

Rate  of  flow  of  blood 150 

Observations  made  on  Pike's  Peak 173 

Respiration,  increase  in 209 

Sequence  in  blood  changes  at  high  altitude 144, 145, 146 

Under  a  decreasing  oxygen  supply 172-180 


438  INDEX. 

Blood  circulation — Continued.  Page. 

Valvular  disease ■ 226 

Vasomotor  control  of  heart 210-211 

Blood,  oxygen  pressure  in 141 

Blood  pressure : 

After  physical  exertion 188 

Capillary 150 

Effects  of  physical  exertion  on 151, 152 

Increase  and  decrease  in,  during  rebreathing  test 177, 178 

Oxygen  pressure  of,  at  high  altitudes 159, 160 

Tests  before  and  after  a  flight 191 

Venous 146, 149 

Venous,  method  of  obtaining 180 

Bone  and  joint  tests 80 

Breathing.     {See  Rebreathing.) 

British  front,  report  of  medical  officers  on  visit  to 121 

Calisthenics,  flying 395,  396 

Exercises 397,  398,  399 

Radically  new 396,  397 

Caloric  test 238 

Capillary  blood  pressure 146, 150 

Carbon  dioxide  capacity  of  the  blood 202 

Carbon  dioxide  in  the  blood,  effect  on  respiratory  center 153, 154 

Carbon  dioxide  pressure 155 

Chair-turning  tests 75 

Chart  1 167 

Chart  2 174 

Chart  3 178 

Chart  4 181 

Charts 185 

Chart  6 187 

Chart  7 190 

Chart  8 192 

Chart  9 194 

Chart  9a 199 

Chart  10 195 

Chart  10a 205 

Chart  11 219 

Chart  12 220 

Chart  13 221 

Chart  14 222 

Chart  15 223 

Chart  16 224 

Chart  17 225 

Charts 8, 9, 18, 19, 27, 31 

Chest  measurement 79 

Chief  surgeon: 

Relation  of,  to  Surgeon  General 100 

Research  board  authorized  for  duty  in  office  of 1 00 

Circulatory  changes,  causes  of 151 

Cities  in  which  examining  units  have  been  established 44, 

45,  46,  47,  48, 49,  50,  51,  52,  53,  54 

Classification,  analysis  of 349 

Examinations  (table) 349 

Classification  as  to  fitness  of  fliers  for  different  types  of  air  activities 14, 23 


INDEX.  439 

Page. 

Classification  examination ; 345,  346,  347, 348,  349 

Average  age  of  persons  undergoing 349 

Directions  for 350 

Duties  of  officers 352,  353 

Routine  for  record  keeping 353,  354,  355 

Routine  for .' 350,  351,  352 

Code  test , 311 

Color  test 42,  68 

Commanding  General,  Air  Service,  report  of,  on  study  of  the  oxygen  question 

abroad 100 

Comparison  of  ground  and  air  service  conditions 229 

Continuous  reaction  tests 316 

Corbett,  Capt.  Dudley,  article  by,  relative  to  medical  service  attached  to  Royal 

Fhdng  Corps 114 

Cowl,  change  in,  to  avoid  injuries  in  crashes 32 

Crampton's  vasomoter  tone  index  in  rebreathing  test 186 

Deaf-mutes,  experiments  with 243,  246 

Deep  sensibility  on  the  ground  compared  with  in  airplane 230 

Dermagraphia,  tests  for,  before  and  after  flying .*....  338,  339 

Deterioration  of  the  individual  flier 295,  296 

Diastolic  blood  pressure: 

After  physical  exercise 189 

Before  and  after  a  flight 191 

Increase  and  decrease  in,  during  rebreathing  test 177, 179 

Digestive  system 81 

Dilution  test: 

Apparatus  used  for 169 

Comparison  of,  with  rebreathing  test 169 

Dkections  for  clinician  as  to  rating 357,  358 

Distance,  judgment  of,  and  stereoscopic  vision 266,  282 

Dreyer  oxygen  apparatus 32,  429 

Dynamometer  test 311,  312 

Ear: 

Examination  of,  details  regarding 233 

Otologic  research  previous  to  the  war 227 

The  ear  in  "stunt"  flying 258-262 

Vertigo  effects  of  ear  stimulation 260 

Ear  tests 73 

Motion-sensing 75 

Editorial  insert 323 

Electrically  warmed  clothing 32 

Equilibrium  and  orientation,  maintenance  of 294 

Equilibrium  tests 232 

Equipment,  ophthalmological,  for  branch  laboratories 361, 362 

Eustachian  tubes,  condition  of ,  one  of  vital  importance 235 

Examining  boards  for  Air  Service  established  in  principal  cities 37 

Examining  units: 

Cities  in  which  established 44,  45, 46,  47,  48, 49,  50,  51 ,  52,  53,  54 

New  methods  and  standards  established  for,  by  medical  officers 41,  42,  43 

Physical,  statistical  reports  of  results  of ■ 83,  84,  85,  86,  87,  88 

Examination  of  applicants  for  air  service 37 

Examination,  physical,  of  applicants,  form  used 17 

Exercises  for  aviators 404, 405, 406,  407,  408,  409 


440  INDEX. 

Page. 

Experiments  in  linear  upward  and  downward  directions 242-245 

Normals 242 

Deaf-mutes 243 

Tabetics 244 

Eye: 

Effect  of  altitude  on 270 

Examination,  routine,  during  rebreathing  test 360,  361 

Goggles,  recommendations  as  to 271 

Eye  tests: 

Accommodation  test  object 278,  289 

Apparatus  employed 291 

Binocular  field  of  vision 268 

Binocular  vision  tested  by  means  of  a  stereoscope 266 

Chart 274 

Color  vision 68,265,268,279,283 

Convergence  power 287 

Equilibrium ,  importance  of  eye  in  maintaining 269 

External  ocular  examination 67,  264 

Field  of  binocular  vision  and  binocular  fixation 283 

Field  of  vision 67, 265,  268, 272, 284 

Fundus,  examination  of,  during  rebreathing  and  low-pressure  experiments        296 

Intraocular  tension 285 

Iris  reaction  during  rebreathing  and  low-pressure  experiments 290 

Jenning's  color  test 279 

Maddox  rod  test 276 

Muscle  balance 68,  255,  268,  276 

Muscle  balance  and  muscle  strength 283 

Ocular  movements 66,  264 

Ocular  nystagmus 67,  264 

Ophthalmoscopic  findings 68,  266 

Ophthalmological  examination  of  the  flier  during  low  oxygen 275 

Perception  of  motion  and  its  direction 269 

Perception  of  motion  by  the  retina 285 

Preliminary  report  of  the  research  work  of  the  ophthalmological  department       281 

Pupillary  reactions 67,264,279 

Reaction  of  the  iris  to  light  and  accommodation 280 

Reaction  time 282 

Reeve's  wedge  test 275,  278 

Retinal  sensiti\dty 270,  275,  288 

Screen  and  parallax  test 277 

Stereoscopic  vision 65,  264, 280,  282 

Test  types 72 

Tobacco,  effect  of,  upon  the  visual  acuity 282,  291 

Value  of,  in  aviation 266-270 

Visual  acuity 70,  266,  268,  275 

Fainting 213,  214,  216 

Falling  test 238 

"Feel  of  the  airship,"  experimental  studies  on 246 

Flight  surgeon : 

Duties  of 14, 29,  33,  377 

Reexaminations  conducted  by 378 

Food  problem  of  the  flier 411 

France,  report  of  Commanding  General  Air  Service  in  connection  with  visit  to . .       100 


INDEX.  441 

Page. 

French  Medical  Aviation  Service 123 

Lecture  by  Dr.  Guilbert  attached  to 124 

Gas  analyzer: 

Description  of  apparatus 370, 371 

Use  of  apparatus 371, 372 

Gases: 

Dcterraination  of 156 

Intestinal 186, 187 

German  medical  service  for  study  of  the  flier *. 97 

Goggles: 

"  Noviol "  type  of,  furnished 32 

Recommendations  as  to 271 

Handwriting  tests: 

Penalties  for  errors  in 812, 313 

Record  of  Pvt.  Wickman 313 

Heart: 

Arrhythmia 218 

Arteriosclerosis 217 

"  Athletic  "  hearts 226 

Effects  on,  at  high  altitude 206 

Effects  of  low  atmospheric  pressure  on  the  circulatory  system 205 

Efficiency  of 207 

Fainting  in  the  air 213, 214 

Output  of 150 

Increased  at  high  altitude 151 

Physiology  of  exercise  compared  with  aviation 216 

Valvular  disease 226 

Vasomotor  control 210,  211 

Heart  beat: 

Augmentation  of,  at  high  altitudes 147 

Effect  of  physical  training  on 164, 165 

Frequency  of 175 

Rate  of,  at  14,000  feet 147 

Heart  disease,  valvular,  notes  on  the  diagnosis  of 358,  359 

Height  and  weight,  tests  in 79 

Hemoglobin  in  the  blood,  occm'rence  of,  during  short  exposures  to  low  oxygen.       193 

Immelmann  turn 262 

Inefficiency,  causes  leading  to 336 

Intestinal  gases 184 

Italian  Medical  Aviation  Service 131 

Jennings's  color  test 42 

Kymograph,  description  of 369,  370 

Laboratories,  branch,  ophthalmological  equipment  for 361, 362 

Lombard's  observatien  on  low  and  high  altitudes 150 

Loop 261 

Low-pressure  chamber,  Miueola  laboratory 343,  344, 345 

Mass  athletics 395 

Mathematical  tests 315 

Medical  officers,  reports  of,  returning  from  England,  France,  and  Italy 95-135 

Medical  Research  Laboratory: 

Research  work  of,  in  Minoola 205 

Medical  ser\dce  attached  to  Royal  Flying  Corps 105, 110, 121 

Medical  ser\'ice,  relation  to  forces  abroad 100 

Medical  units,  establishment  of,  for  examination  of  applicants, 20 


442  INDEX. 

Page. 

Memory  tests 314 

Mental  hygiene,  as  related  to  aviator 337 

Mental  processes,  effect  of  low  oxygen  upon 26 

Messes,  instructions  regarding,  by  nutrition  officer 418 

Motion-sensing: 

Experience  and  education  in 253 

Importance  of 230 

Observations  on,  during  airplane  flights 247-253 

Explaaation  of  charts 248-253 

Motion-sensing  tests 75 

Motor  coordinations 229 

Motor  tendencies 303-304 

Mountain  sickness 138, 139, 140, 141, 142 

Cause  of  8}anptoms 140 

Nervous  type 139 

Muscle  balance 68 

Naso-pharynx  defects,  number  rejected  on  account  of 84 

Naso-pharynx  tests 73-75 

Naces : 73 

Tonsils 74 

Adenoids '      74 

Eustachian  tubes 75 

Nervous  system,  irritability  of 165, 166 

Nervous  system  tests 80 

Neurology  and  Psychiatry,  Department  of 330 

Nei'\'0us  and  mental  diseases 330 

Temperament 330,  331 

Neiu-o-psychiatric  examination 337,  338 

Nose,  examination  of,  details  regarding 234 

Nutrition  officer: 

Duties  of 15,35 

Mess  force,  instructions  to,  by 418 

Need  for 414 

Nystagmus 76 

Analyzed  report  on 323,  324,  325,  326,  327, 328 

Duration  of 85 

Experiments 320,  321,  322 

Observation  tests 314,  315 

Ocular  movements,  effect  of  repetition  upon 316,  317, 318,  319 

Ocular  nystagmus 67 

Optimum  type  of  subject 208,  213 

Organization  for  examination  of  applicants  for  air  service 37 

Orientation,  methods 328,  329 

Orientator,  otologic  apparatus  known  as,  used  in  laboratory  work 262 

Otologic  problems  under  consideration  at  the  Medical  Research  Laboratory.  . .       240 

Otologic  research  previous  to  the  war 227 

Otologist,  special  care  in  selecting 228 

Oxygen: 

Apparatus  for  supplying 25, 426 

Description  and  instructions  for  operating 429 

Blood  circulation  under  a  decreasing  supply  of 172-180 

Breathing  under  decreasing  supply  of 170-172 

Deficiency 296 

Psychological  effects  of 297 


INDEX.  443 

Oxygen — Continued.  Page. 

Demands  of  body  for,  during  rapid  ascents 168 

"Flack"  test lO.S 

Interviews  with  British  commanding  officers  regarding  use  of 101 

Low,  effect  of,  upon  mental  processes 26 

Low,  effect  of,  upon  vision 26 

Pressure  in  blood 141, 146, 155, 159, 160 

Pulse  rate  as  indicator  of  want  of 17?> 

Secretion '.* 164 

Tension,  low,  psychological  investigations  with 310 

Value  of,  in  altitude  flying 423 

Physical  condition: 

A\'iator 215 

Blank  for  examination 228 

Defects  cause  of  90  per  cent  of  accident? 207 

Falling  test 238 

Requirements  fixed  by  Chief  Surgeon,  Air  Medical  Service 228 

Temporary  indispositions 215 

Physical  director,  duty  of 14,  34 

Phj'sical  examination: 

Adenoids 235 

Applicants  in  first  call 263-266 

Blank  609  A.  G.  O.  for  use  in 55,58 

Bone  and  joint  tests 80 

Caloric  test 238 

Chest  measurement 79 

Digestive  system 81 

Ear 233 

Ear  tests 73 

Eustachian  tubes 235 

Eye  tests 65-73 

Form  used  in 17 

Genito-urinaiy  system 81 

Height  and  weight 79 

Instructions  governing  medical  officer  in  making 61-64 

Eye  determination 61 

Ear  determination 63 

Nose 63 

Equilibrium  test 63 

Static  test 63 

"Liberty  motor  "  scheme  for  conducting  work  of  examining  units 56 

Medical  units  for  examination  of  applicants  established  in  35  cities 20 

Method  of  conducting 55 

Methods  of,  in  selection  of  fliers 17 

Naso- pharynx  tests 73-75 

Nervous  system 80 

Nose 234 

Nystagmus 236 

Pointing  test 236 

Rates  of  failure  in  eye  tests 84 

Respiratory  syst  :ra 80 

Results  of,  methods  used  in  posting  (folder) follows  p.  93 

Results  of,  satisfactory  to  Chief  Surgeon 233 

Revision  of 99 

Schedule  of  organization 58 

89118—19 30 


444  INDEX. 

Physical  examination — Continued.  Page. 

Skin  tests 80 

Static  and  dynamic  tests 75 

Teeth 81,  235 

Throat 234 

Tonsils,  condition  of 234 

Turning-chair  tests 75 

Uniform  tests  throughout  all  examining  units 20 

Urinalysis 81 

Vascular  system 81 

Vestibular  tests 235 

Physical  Examining  Units ". 37,  38,  39 

Establishing  of 41, 228 

San  Antonio,  Tex. — 

Number  of  applicants  accepted 87 

Number  of  applicants  rejected 87 

System  of  keeping  records  for 38 

Report  of 87 

Technique  developed  in  examinations  by 38,  39 

Washington,  D.  C.  report  of 88,  89,  90 

Physical  exercise  compared  with  aviation 216 

Physical  training  for  aviators 402 

Exercises 404,  405,  406,  407,  408,  409 

Proper  clothing  and  apparatus 402 

Physiological  data,  physiologist  to  obtain  and  interpret 364 

Physiological  responses,  rating  of 366 

Pike's  Peak: 

Blood  circulation  observations  on 173 

Effect  of  altitude  on  man 146 

Pointing  tests 236 

Pressures: 

Arterial *. 146, 148 

Capillary 146 

Psychologist,  instructions  to 363,  364 

Psychology  Department 293 

Psychology,  relation  of,  to  the  a\  iator 293 

Pulse  and  blood  pressure  study,  preliminary 246, 247 

Pulse  rate 147, 148 

After  physical  exertion 188 

As  indicator  of  oxygen  want 173 

Changes  in,  during  exposure  to  lovr  oxygen  pressure 203 

Effects  of  physical  exertion  on 151, 152 

Ideal  for  flying  officer,  as  8tate<l  by  Maj.  Fiack  and  Capt.  Bowdler 189 

Influence  of  posture  upon 148 

Test  for  obtaLoing 188 

Tests  before  and  after  a  flight 191 

Rating  scheme 305,  306, 307 

Reactor,  apparatus  for,  instructions  for 302, 303, 304 

Rebreathing  machine 342 

Adjustment  of 301 

Conditions  established  by 296 

Operation  of,  special  test 368,  369 

Preparation  of 367 

Simple  form  of ,,.,...,... , . , , , 342,  343 


INDEX.  445 

Rebreathing  tests:  Page. 

Alveolar  air,  analysis  of,  during  test 17R 

Alveolar  air  presstires,  experiments  made  to  show  changes  in 198 

Apparatus  for  testing  of 169 

Blood  pressure  after  physical  exertion 188 

(,!arbon  dioxide  capacity  of  the  blood 202 

Comparison  of  the  rebreathing  test  and  the  dilution  test 169 

Conditions  corresponding  to  altitudes  of  15,000  to  20,000  feet 19(i,  197 

Control  teats  to  determine  reliability  of  rebieatbiug  tests 197 

Crampton's  vasomotor  tone  index  used  in 186 

Deep  breathing,  advantage  of,  over  shallow  breathing 170 

Demands  of  body  for  oxygen  during  rapid  ascents 168 

Diastolic  blood  pressure — 

After  physical  exercise 189 

Increase  and  decrease  in 177, 179 

Diastolic  murmurs :-!58 

Directions  to  clinician  as  to  conduct  of 355, 356,  357 

Duration  of 176 

Hemoglobin  changes 202 

Incidental  results  of  work  on 307,  308 

Instructions  to  the  physiologist  as  to 364 

Intestinal  gases 184 

Length  of  time  taken  to  reach  a  low  oxygen  test 176 

Observations  made  on  Pike's  Peak  in  regard  to 156, 157 

Physiology  of  rebreathing  and  a\aation 168-254 

Power  to  hold  the  breath 182 

Pulse  rate — 

After  physical  exertion 188 

Test  for  obtaining 188 

Rates  of,  under  test 170, 171 

Relative  value  of  the  compensatory  factors 196-198,  207 

Routine  eye  examination  during 360,  361 

Skin-color  changes  diu-ing 176 

SystoUc  blood  pressure — 

After  physical  exercise 189 

Increase  and  decrease  in 177, 179 

Systolic  miUTnurs 358 

Turning-chair  tests 75,  232 

Vasomotor  tone  and  endurance  of  low  oxygen 186 

Venous  blood  pressure,  increase  and  decrease  in 180-182 

Method  of  obtaining 180 

Vital  capacity  of  the  lungs 182-186 

Volume  of  air  breathed  per  minute 202 

When  under  the  action  of  progressive  decrease  in  the  oxygen  supply.  .  .   170-172 

Recording  apparatus,  preparation  of 367,  368 

Reports  of  medical  officers  returning  from  England.  France,  and  Italy 95-135 

Research  board  authorized  for  duty  in  office  of  chief  surgeon 100 

Respiration  at  liigli  altitude >53 

Respiratory  system  tests 80 

Royal  Fl\-ing  Corps: 

Article  by  Capt.  Dudley  Corbett  relative  to 114 

Articles  by  Maj.  J.  L.  Birley  relative  to  medical  ser\'ice  attached  to. ."  105, 110, 121 

Rubber  connections 374 

San  Antonio,  Tex.,  physical  examining  unit  at,  report  of 87,  88 

Schneider  and  Sisco's  observations  on  the  lack  of  supply  of  oxygen 150, 151 

"  Setting-up  "  exercises 403 

Shock  absorber  for  use  in  lashing  safety  belt  to  machine 32 


446  INDEX, 

Page. 

Skin-color  changes  during  rebreathing  test 176 

Skin  tests 80 

Smoking  the  drum 368 

Solutions  used  as  absorbents 374 

Spinning  nose  dive 261 

Spiral  maneuver 261 

Spirometer: 

Calibration  of 370 

Respiration  data  obtained  from  kymograph  record  of 364,  365 

' ' Stale  athlete,"  remarks  on 165 

"Stale  pilot,"  remarks  on 165 

Staleness  in  aviators,  rebreathing  test  in  determining 26 

Standard  test:  ( 

Apparatus  for 300,  301 

Method  of  conducting 301,  302 

Standardized  table 403,  404 

Static  and  dynamic  tests 76 

Stereoscopic  vision 65 

Stopcocks 373 

Strohl's  comparison  of  hearts  of  Alpine  and  Moor  snowbirds. .  .♦, 153 

"Stunt "  flying 26,  258-262 

Immelmann  turn 262 

Loop 261 

Spinning  nose  dive 261 

Tight  spiral 261 

Surgeon  General,  relation  of  chief  surgeon  to 100 

Swimming  pools,  need  of 401 

Symbols  and  their  significance 304,  305 

Systolic  blood  pressure: 

After  physical  exercise 189 

Before  and  after  a  flight 191 

Increase  and  decrease  in,  diuing  rebreathing  test 177, 179 

Tactical  discrimination 311 

Teeth,  examination  of 81,  235 

Throat,  examination  of,  details  regarding 234 

Tight  spiral  maneuver 261 

Tissandier,  description  by,  of  high  altitude  ascent 140 

Tobacco: 

Effects  of,  on  aviators 293 

Effect  of,  upon  the  eye 282,  291 

Tonsils,  examination  of 234 

Turning-chair  tests 75 

Uniform  tests  throughout  all  physical  examining  units 20 

Valvular  disease  of  the  heart 226 

Vascular  system  requirements 85 

Venous  blood  pressure 149, 150 

Increase  and  decrease  in,  during  rebreathing  test 180-182 

.  Method  of  obtaining 180 

Vertigo 235,236 

Vestibular  sense,  its  motion-sensing  utility  as  great  in  the  air  as  on  the  ground. .       231 

Vision,  effect  of  low  oxygen  upon 26 

Vision  on  the  ground  compared  with  in  the  air 230 

Weight,  tests  in 79 

Whirling  artists,  dancers,  and  equilibrists,  tests  of 254-256 

Wright  biplane,  interest  in,  by  European  nations  when  first  invented 10 


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